MFS VARIABLE INSURANCE TRUST, 497, 1999-05-24

MFS VARIABLE INSURANCE TRUST
497, 1999-05-24

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[logo]MFS(R)
INVESTMENT MANAGEMENT
75 YEARS
WE INVENTED THE MUTUAL FUND(R)

MFS(R) VARIABLE INSURANCE TRUST(SM)

MAY 1, 1999

Prospectus

MFS(R) CAPITAL OPPORTUNITIES SERIES
MFS(R) RESEARCH SERIES
MFS(R) TOTAL RETURN SERIES
MFS(R) UTILITIES SERIES

- --------------------------------------------------------------------------------

This Prospectus describes four of the series of the MFS Variable Insurance
Trust (referred to as the trust):

1. MFS Capital Opportunities Series seeks capital appreciation (referred to as
the Capital Opportunities Series);

2. MFS Research Series seeks to provide long-term growth of capital and future
income (referred to as the Research Series);

3. MFS Total Return Series seeks primarily to provide above-average income
(compared to a portfolio invested entirely in equity securities) consistent
with the prudent employment of capital, and secondarily to provide a
reasonable opportunity for growth of capital and income (referred to as the
Total Return Series); and

4. MFS Utilities Series seeks capital growth and current income (income above
that available from a portfolio invested entirely in equity securities)
(referred to as the Utilities Series).

The Securities and Exchange Commission has not approved the series' shares or
determined whether this prospectus is accurate or complete. Anyone who tells
you otherwise is committing a crime.
<PAGE>

<TABLE>
<CAPTION>
TABLE OF CONTENTS Page
<S> <C> <C>
I Expense Summary ............................................ 1
II Risk Return Summary ........................................ 2
1. Capital Opportunities Series ............................ 2
2. Research Series ......................................... 5
3. Total Return Series ..................................... 7
4. Utilities Series ........................................ 11
III Certain Investment Strategies and Risks .................... 16
IV Management of the Series ................................... 16
V Description of Shares ...................................... 16
VI Other Information .......................................... 17
VII Financial Highlights ....................................... 18
Appendix A -- Investment Techniques and Practices .......... A-1
</TABLE>
<PAGE>

The trust offers shares of its 15 series to separate accounts established
by insurance companies in order to serve as investment vehicles for
variable annuity and variable life insurance contracts and to qualified
pension and retirement plans. Each of these series is managed by
Massachusetts Financial Services Company (referred to as MFS or the
adviser). Four of these series are described below.

I EXPENSE SUMMARY

> Expense Table

This table describes the expense that you may pay when you hold shares of
the series. These fees and expenses do not take into account the fees and
expenses imposed by insurance companies through which your investment in a
series may be made.

Annual Series Operating Expenses (expenses that are deducted from a series'
assets):

<TABLE>
<CAPTION>
Capital Total
Opportunities Research Return Utilities
Series Series Series Series
------------------ ---------- ---------- ----------
<S> <C> <C> <C> <C>
Management Fee .................................... 0.75% 0.75% 0.75% 0.75%
Other Expenses(1) ................................. 0.36% 0.11% 0.16% 0.26%
----- ---- ---- ----
Total Annual Series Operating Expenses(1) ......... 1.11% 0.86% 0.91% 1.01%
Expense Reimbursement ............................ (0.09)%(2) -- -- --
----- ---- ---- ----
Net Expenses(1) .................................. 1.02% 0.86% 0.91% 1.01%
</TABLE>

---------
(1) Each series has an expense offset arrangement which reduces the series'
custodian fee based upon the amount of cash maintained by the series with
its custodian and dividend disbursing agent. Each series may enter into
other such arrangements and directed brokerage arrangements, which would
also have the effect of reducing the series' expenses. Expenses do not
take into account these expense reductions, and are therefore higher than
the actual expenses of the series.
(2) MFS has contractually agreed to bear expenses for these series, subject
to reimbursement by these series, such that each such series' "Other
Expenses" shall not exceed 0.25% of the average daily net assets of the
series during the current fiscal year. The payments made by MFS on behalf
of each series under this arrangement are subject to reimbursement by the
series to MFS, which will be accomplished by the payment of an expense
reimbursement fee by the series to MFS computed and paid monthly at a
percentage of the series' average daily net assets for its then current
fiscal year, with a limitation that immediately after such payment the
series' "Other Expenses" will not exceed the percentage set forth above
for that series. The obligation of MFS to bear a series' "Other Expenses"
pursuant to this arrangement, and the series' obligation to pay the
reimbursement fee to MFS, terminates on the earlier of the date on which
payments made by the series' equal the prior payment of such reimbursable
expenses by MFS, or December 31, 2004. MFS may, in its discretion,
terminate this contractual arrangement at an earlier date, provided that
the arrangement will continue for each series until at least May 1, 2000,
unless terminated with the consent of the board of trustees which oversees
the series.

> Example of Expenses

These examples are intended to help you compare the cost of investing in
the series with the cost of investing in other mutual funds. These
examples do not take into account the fees and expenses imposed by
insurance companies through which your investment in a series may be made.

The examples assume that:

o You invest $10,000 in the series for the time periods indicated and you
redeem your shares at the end of the time periods;

o Your investment has a 5% return each year and dividends and other
distributions are reinvested; and

o The series' operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions
your costs would be:

<TABLE>
<CAPTION>
Period
----------------------------------------
Series 1 Year 3 Years 5 Years 10 Years
- --------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Capital Opportunities Series $104 $344 $603 $1,344
Research Series 88 274 477 1,061
Total Return Series 93 290 504 1,120
Utilities Series 103 322 558 1,236
</TABLE>

1
<PAGE>

II RISK RETURN SUMMARY

Investment strategies which are common to all series are described under
the caption "Certain Investment Strategies."

1: Capital Opportunities Series
........................................................................ .

> Investment Objective

The series' investment objective is capital appreciation. The series'
objective may be changed without shareholder approval.

> Principal Investment Policies

The series invests, under normal market conditions, at least 65% of its
total assets in common stocks and related securities, such as preferred
stocks, convertible securities and depositary receipts for those
securities. The series focuses on companies which MFS believes have
favorable growth prospectus and attractive valuations based on current and
expected earnings or cash flow. The series' investments may include
securities listed on a securities exchange or traded in the
over-the-counter markets.

MFS uses a bottom-up, as opposed to a top-down, investment style in
managing the equity-oriented funds (such as the series) it advises. This
means that securities are selected based upon fundamental analysis
performed by the series' portfolio manager and MFS' large group of equity
research analysts.

The series may invest in foreign securities (including emerging market
securities), through which it may have exposure to foreign currencies.

> Principal Risks

The principal risks of investing in the series and the circumstances
reasonably likely to cause the value of your investment in the series to
decline are described below. As with any non-money market mutual fund, the
share price of the series will change daily based on market conditions and
other factors. Please note that there are many circumstances which could
cause the value of your investment in the series to decline, and which
could prevent the series from achieving its objective, that are not
described here.

The principal risks of investing in the series are:

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market conditions
or disappointing earnings results.

o Company Risk: Prices of securities react to the economic condition of the
company that issued the security. The series' equity investments in an
issuer may rise and fall based on the issuer's actual and anticipated
earnings, changes in management and the potential for takeovers and
acquisitions.

o Over-the-Counter Risk: Over-the-counter (OTC) transactions involve risks
in addition to those associated with transactions in securities traded on
exchanges. OTC-listed companies may have limited product lines, markets
or financial resources. Many OTC stocks trade less frequently and in
smaller volume than exchange-listed stocks. The values of these stocks
may be more volatile than exchange-listed stocks, and the series may
experience difficulty in establishing or closing out positions in these
stocks at prevailing market prices.

o Foreign Securities Risk: Investments in foreign securities involve risks
relating to political, social and economic developments abroad, as well
as risks resulting from the differences between the regulations to which
U.S. and foreign issuers and markets are subject:

> These risks may include the seizure by the government of company
assets, excessive taxation, withholding taxes on dividends and
interest, limitations on the use or transfer of portfolio assets, and
political or social instability.

> Enforcing legal rights may be difficult, costly and slow in foreign
countries, and there may be special problems enforcing claims against
foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there may be
less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S. markets.

2
<PAGE>

> Foreign securities often trade in currencies other than the U.S.
dollar, and the series may directly hold foreign currencies and
purchase and sell foreign currencies through forward exchange
contracts. Changes in currency exchange rates will affect the series'
net asset value, the value of dividends and interest earned, and gains
and losses realized on the sale of securities. An increase in the
strength of the U.S. dollar relative to these other currencies may
cause the value of the series to decline. Certain foreign currencies
may be particularly volatile, and foreign governments may intervene in
the currency markets, causing a decline in value or liquidity in the
series' foreign currency holdings. By entering into forward foreign
currency exchange contracts, the series may be required to forego the
benefits of advantageous changes in exchange rates and, in the case of
forward contracts entered into for the purpose of increasing return,
the series may sustain losses which will reduce its gross income.
Forward foreign currency exchange contracts involve the risk that the
party with which the series enters the contract may fail to perform its
obligations to the series.

o Emerging Markets Risk: Emerging markets are generally defined as
countries in the initial stages of their industrialization cycles with
low per capita income. Investments in emerging markets securities involve
all of the risks of investments in foreign securities, and also have
additional risks:

> All of the risks of investing in foreign securities are heightened by
investing in emerging markets countries.

> The markets of emerging markets countries have been more volatile than
the markets of developed countries with more mature economies. These
markets often have provided significantly higher or lower rates of
return than developed markets, and significantly greater risks, to
investors.

o As with any mutual fund, you could lose money on your investment in the
series.

An investment in the series is not a bank deposit and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other
government agency.

> Bar Chart and Performance Table

The bar chart and performance table below are intended to indicate some of
the risks of investing in the series by showing changes in the series'
performance over time. The performance table also shows how the series
performance over time compares with that of one or more broad measures of
market performance. The chart and table provide past performance
information. The series' past performance does not necessarily indicate how
the series will perform in the future. The returns shown do not reflect
fees and charges imposed under the variable annuity and life insurance
contracts through which an investment may be made. If these fees and
charges were included, they would reduce these returns.

Bar Chart

The bar chart shows changes in the annual total returns of the series'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[bar chart]
1997 26.47%
1998 26.80%

During the period shown in the bar chart, the highest quarterly return was
24.04% (for the calendar quarter ended December 31, 1998) and the lowest
quarterly return was (13.91)% (for the calendar quarter ended September 30,
1998).

3
<PAGE>

Performance Table

This table shows how the average annual total returns of the series' shares
compares to a broad measure of market performance and assumes the
reinvestment of distributions.

Average Annual Total Returns as of December 31, 1998
.........................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Capital Opportunities Series* 26.80% 26.33%
Standard & Poor's 500 Composite Index **++ 28.58% 28.16%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations on August 4, 1996, through December 31, 1998.
++ Source: CDA/Wiesenberger. "Life" refers to the period from September
1, 1996, through December 31, 1998.
** The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.

> Portfolio Manager

Maura A. Shaughnessy, a Senior Vice President of the Adviser, has been
employed as a portfolio manager by the Adviser since 1991. Ms. Shaughnessy
has been the series' portfolio manager since February 24, 1999.

4
<PAGE>

2: Research Series
........................................................................ .

> Investment Objective

The series' investment objective is long-term growth of capital and future
income. The series' objective may be changed without shareholder approval.

> Principal Investment Policies

The series invests, under normal market conditions, at least 80% of its
total assets in common stocks and related securities, such as preferred
stocks, convertible securities and depositary receipts. The series focuses
on companies that MFS believes have favorable prospects for long-term
growth, attractive valuations based on current and expected earnings or
cash flow, dominant or growing market share, and superior management. The
series may invest in companies of any size. The series' investments may
include securities traded on securities exchanges or in the
over-the-counter markets.

A committee of investment research analysts selects portfolio securities
for the series. This committee includes investment analysts employed not
only by MFS, but also by MFS International (U.K.) Limited, a wholly owned
subsidiary of MFS. The committee allocates the series' assets among various
industries. Individual analysts then select what they view as the
securities best suited to achieve the series' investment objective within
their assigned industry responsibility.

The series may invest in foreign equity securities through which it may
have exposure to foreign currencies.

> Principal Risks

The principal risks of investing in the series are:

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market conditions
or disappointing earnings results.

o Over-the-Counter Risk: Over-the-counter (OTC) transactions involve risks
in addition to those incurred by transactions in securities traded on
exchanges. OTC listed companies may have limited product lines, markets
or financial resources. Many OTC stocks trade less frequently and in
smaller volume than exchange-listed stocks. The values of these stocks
may be more volatile than exchange-listed stocks, and the series may
experience difficulty in purchasing or selling these securities at a fair
price.

o Foreign Markets Risk: Investing in foreign securities involves risks
relating to political, social and economic developments abroad, as well
as risks resulting from the differences between the regulations to which
U.S. and foreign issuers and markets are subject:

> Enforcing legal rights may be difficult, costly and slow in foreign
countries, and there may be special problems enforcing claims against
foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there may be
less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S. markets.

5
<PAGE>

be particularly volatile, and foreign governments may intervene in the
currency markets, causing a decline in value or liquidity in the
series' foreign currency holdings. By entering into forward foreign
currency exchange contracts, the series may be required to forego the
benefits of advantageous changes in exchange rates and, in the case of
forward contracts entered into for the purpose of increasing return,
the series may sustain losses which will reduce its gross income.
Forward foreign currency exchange contracts involve the risk that the
party with which the series enters the contract may fail to perform its
obligations to the series.

o As with any mutual fund, you could lose money on your investment in the
series.

An investment in the series is not a bank deposit and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other
government agency.

> Bar Chart and Performance Table

The bar chart and performance table below are intended to indicate some of
the risks of investing in the series by showing changes in the series'
performance over time. The performance table also shows how the series'
performance over time compares with that of one or more broad measures of
market performance. The chart and table provide past performance
information. The series' past performance does not necessarily indicate how
the series will perform in the future. The returns shown do not reflect
fees and charges imposed under the variable annuity and life insurance
contracts through which an investment may be made. If these fees and
charges were included, they would reduce these returns.

Bar Chart

The bar chart shows changes in the annual total returns of the series'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[bar chart]
1996 22.33%
1997 20.26%
1998 23.39%

During the period shown in the bar chart, the highest quarterly return was
21.65% (for the calendar quarter ended December 31, 1998) and the lowest
quarterly return was (14.66)% (for the calendar quarter ended September 30,
1998).

Performance Table

This table shows how the average annual total returns of the series' shares
compares to a broad measure of market performance and assumes the
reinvestment of distributions.

Average Annual Total Returns as of December 31, 1998
.........................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Research Series* +23.39% +22.52%
Standard & Poor's 500 Composite Index**+ +28.58% +28.16%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations, July 26, 1995, through December 31, 1998.
** Source: CDA/Wiesenberger. "Life" refers to the period from August 1,
1995, through December 31, 1998.
+ The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.

> Portfolio Manager

The series is currently managed by a committee comprised of various equity
research analysts employed by the Adviser. The committee has managed the
series since its inception.

6
<PAGE>

3: Total Return Series
...........................................................................

> Investment Objectives

The series' investment objective is primarily to provide above-average
income (compared to a portfolio invested entirely in equity securities)
consistent with the prudent employment of capital. Its secondary objective
is to provide reasonable opportunity for growth of capital and income. The
series' objectives may be changed without shareholder approval.

> Principal Investment Policies

The series is a "balanced fund," and invests in a combination of equity and
fixed income securities. Under normal market conditions, the series
invests:

o at least 40%, but not more than 75%, of its net assets in common stocks
and related securities (referred to as equity securities), such as
preferred stock; bonds, warrants or rights convertible into stock; and
depositary receipts for those securities, and

o at least 25% of its net assets in non-convertible fixed income
securities.

The series may vary the percentage of its assets invested in any one type
of security (within the limits described above) in accordance with MFS's
interpretation of economic and money market conditions, fiscal and monetary
policy and underlying security values.

Equity Investments. While the series may invest in all types of equity
securities, MFS generally seeks to purchase for the series equity
securities, such as common stocks, preferred stocks, convertible securities
and depositary receipts, of companies that MFS believes are undervalued in
the market relative to their long-term potential. The equity securities of
these companies may be undervalued because:

o they are viewed by MFS as being temporarily out of favor in the market
due to

> a decline in the market,

> poor economic conditions,

> developments that have affected or may affect the issuer of the
securities or the issuer's industry, or

o the market has overlooked them.

Undervalued equity securities generally have low price-to-book,
price-to-sales and/or price-to-earnings ratios. The series focuses on
undervalued equity securities issued by companies with relatively large
market capitalizations (i.e., market capitalizations of $5 billion or
more).

As noted above, the series' investments in equity securities include
convertible securities. A convertible security is a security that may be
converted within a specified period of time into a certain amount of common
stock of the same or a different issuer. A convertible security generally
provides:

o a fixed income stream, and

o the opportunity, through its conversion feature, to participate in an
increase in the market price of the underlying common stock.

MFS uses a bottom-up, as opposed to a top-down, investment style in
managing the equity-oriented funds (including the equity portion of the
series) it advises. This means that securities are selected based upon
fundamental analysis performed by the series' portfolio manager and MFS'
large group of equity research analysts.

Fixed Income Investments. The series invests in securities which pay a
fixed interest rate, which include:

o U.S. government securities, which are bonds or other debt obligations
issued by, or whose principal and interest payments are guaranteed or
supported by, the U.S. government or one of its agencies or
instrumentalities,

o mortgage-backed and asset-backed securities, which represent interests in
a pool of assets such as mortgage loans, car loan receivables, or credit
card receivables. These investments entitle the series to a share of the
principal and interest payments made on the underlying mortgage, car
loan, or credit card. For example, if the series invests in a pool that
includes your mortgage loan, a share of the principal and interest
payments on your mortgage would pass to the series, and

o corporate bonds, which are bonds or other debt obligations issued by
corporations or other similar entities.

In selecting fixed income investments for the series, MFS considers the
views of its large group of fixed income portfolio managers and research
analysts. This group periodically assesses the three-month total return
outlook for various segments of the fixed income markets. This three-month
"horizon" outlook is used by the portfolio manager(s) of MFS' fixed-income
oriented series (including the fixed-income portion

7
<PAGE>

of the series) as a tool in making or adjusting a series' asset allocations
to various segments of the fixed income markets. In assessing the credit
quality of fixed-income securities, MFS does not rely solely on the credit
ratings assigned by credit rating agencies, but rather performs its own
independent credit analysis.

> Principal Risks

The principal risks of investing in the series are:

o Allocation Risk: The series will allocate its investments between equity
and fixed income securities, and among various segments of the fixed
income markets, based upon judgments made by MFS. The series could miss
attractive investment opportunities by underweighting markets where there
are significant returns, and could lose value by overweighting markets
where there are significant declines.

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market conditions
or disappointing earnings results.

o Undervalued Securities Risk: Prices of securities react to the economic
condition of the company that issued the security. The series' equity
investments in an issuer may rise and fall based on the issuer's actual
and anticipated earnings, changes in management and the potential for
takeovers and acquisitions. MFS will invest in securities that are
undervalued based on its belief that the market value of these securities
will rise due to anticipated events and investor perceptions. If these
events do not occur or are delayed, or if investor perceptions about the
securities do not improve, the market price of these securities may not
rise or may fall.

o Interest Rate Risk: When interest rates rise, the prices of fixed income
securities in the series' portfolio will generally fall. Conversely, when
interest rates fall, the prices of fixed income securities in the series'
portfolio will generally rise.

o Convertible Securities Risk: Convertible securities, like fixed income
securities, tend to increase in value when interest rates decline and
decrease in value when interest rates rise. The market value of a
convertible security also tends to increase as the market value of the
underlying stock rises and decrease as the market value of the underlying
stock declines.

o Maturity Risk: Interest rate risk will generally affect the price of a
fixed income security more if the security has a longer maturity. Fixed
income securities with longer maturities will therefore be more volatile
than other fixed income securities with shorter maturities. Conversely,
fixed income securities with shorter maturities will be less volatile but
generally provide lower returns than fixed income securities with longer
maturities. The average maturity of the series' fixed income investments
will affect the volatility of the series' share price.

o Credit Risk: Credit risk is the risk that the issuer of a fixed income
security will not be able to pay principal and interest when due. Rating
agencies assign credit ratings to certain fixed income securities to
indicate their credit risk. The price of a fixed income security will
generally fall if the issuer defaults on its obligation to pay principal
or interest, the rating agencies downgrade the issuer's credit rating or
other news affects the market's perception of the issuer's credit risk.

o Liquidity Risk: The fixed income securities purchased by the series may
be traded in the over-the-counter market rather than on an organized
exchange and are subject to liquidity risk. This means that they may be
harder to purchase or sell at a fair price. The inability to purchase or
sell these fixed income securities at a fair price could have a negative
impact on the series' performance.

o Mortgage and Asset-Backed Securities:

> Maturity Risk:

+ Mortgage-Backed Securities: A mortgage-backed security will mature
when all the mortgages in the pool mature or are prepaid. Therefore,
mortgage-backed securities do not have a fixed maturity, and their
expected maturities may vary when interest rates rise or fall.

+ When interest rates fall, homeowners are more likely to prepay
their mortgage loans. An increased rate of prepayments on the
series' mortgage-backed securities will result in an unforeseen
loss of interest income to the series as the series may be required
to reinvest assets at a lower interest rate. Because prepayments
increase when interest rates fall, the prices of mortgage-backed
securities does not increase as much as other fixed income
securities when interest rates fall.

+ When interest rates rise, homeowners are less likely to prepay
their mortgage loans. A decreased rate of prepayments lengthens the
expected maturity of a mortgage-backed security. Therefore, the
prices of mortgage-backed securities may decrease more than prices
of other fixed income securities when interest rates rise.

8
<PAGE>

+ Collateralized Mortgage Obligations: The series may invest in
mortgage-backed securities called collateralized mortgage obligations
(CMOs). CMOs are issued in separate classes with different stated
maturities. As the mortgage pool experiences prepayments, the pool
pays off investors in classes with shorter maturities first. By
investing in CMOs, the series may manage the prepayment risk of
mortgage-backed securities. However, prepayments may cause the actual
maturity of a CMO to be substantially shorter than its stated
maturity.

+ Asset-Backed Securities: Asset-backed securities have prepayment
risks similar to mortgage-backed securities.

> Credit Risk: As with any fixed income security, mortgage-backed and
asset-backed securities are subject to the risk that the issuer will
default on principal and interest payments. It may be difficult to
enforce rights against the assets underlying mortgage-backed and
asset-backed securities in the case of default. The U.S. government or
its agencies may guarantee the payment of principal and interest on
some mortgage-backed securities. Mortgage-backed securities and
asset-backed securities issued by private lending institutions or other
financial intermediaries may be supported by insurance or other forms
of guarantees.

o As with any mutual fund, you could lose money on your investment in the
series.

An investment in the series is not a bank deposit and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other
government agency.

> Bar Chart and Performance Table

Bar Chart

The bar chart shows changes in the annual total returns of the series'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[bar chart]
1996 14.37%
1997 21.30%
1998 12.33%

During the period shown in the bar chart, the highest quarterly return was
9.86% (for the calendar quarter ended June 30, 1997) and the lowest
quarterly return was (4.28)% (for the calendar quarter ended September 30,
1998).

9
<PAGE>

Performance Table

This table shows how the average annual total returns of the series' shares
compares to a broad measure of market performance and various other market
indicators and assumes the reinvestment of distributions.

Average Annual Total Returns as of December 31, 1998
.........................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Total Return Series* +12.33% +18.73%
S&P 500 Composite Index**+ +28.58% +30.41%
Lehman Brothers Government/Corporate Bond Index**++ + 9.49% + 8.58%
Average balanced fund# +13.48% +17.64%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations, January 3, 1995, through December 31, 1998.
** Source: CDA/Wiesenberger. "Life" refers to the period from February 1,
1995, through December 31, 1998.
# Source: Lipper Analytical Services, Inc. "Life" refers to the period
from February 1, 1995, through December 31, 1998.
+ The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.
++ The Lehman Brothers Government/Corporate Bond Index is a broad based,
unmanaged, market-value-weighted index of U.S. Treasury and
government-agency securities (excluding mortgage-backed securities) and
investment-grade domestic corporate debt.

> Portfolio Manager

David M. Calabro, a Senior Vice President of MFS, has been employed by the
Adviser as a portfolio manager since 1992. Mr. Calabro is the head of the
series' portfolio management team and a manager of the common stock portion
of the series' portfolio. Geoffrey L. Kurinsky, a Senior Vice President of
MFS, has been employed by the Adviser as a portfolio manager since 1987.
Mr. Kurinsky is the manager of the series' fixed income securities.
Constantinos G. Mokas, a Vice President of MFS, has been a portfolio
manager of the series since April 1, 1998, and has been employed by the
Adviser as a portfolio manager since 1990. Mr. Mokas is the manager of the
series' convertible securities. Lisa B. Nurme, a Senior Vice President of
MFS, has been a portfolio manager of the series since July 19, 1995, and
has been employed by the Adviser as a portfolio manager since 1987. Ms.
Nurme is a manager of the common stock portion of the series' portfolio.
Kenneth J. Enright, a Vice President of MFS, has been employed by the
Adviser as a portfolio manager since 1986 and has been a portfolio manager
of the series since January 15, 1999. Mr. Enright is a manager of the
common stock portion of the series' portfolio.

10
<PAGE>

4: Utilities Series
...........................................................................

> Investment Objective

The series' investment objective is to seek capital growth and current
income (income above that available from a portfolio invested entirely in
equity securities). The series' objective may be changed without
shareholder approval.

> Principal Investment Policies

The series invests, under normal market conditions, at least 65% of its
total assets in equity and debt securities of domestic and foreign
companies in the utilities industry. MFS considers a company to be in the
utilities industry if, at the time of investment, MFS determines that a
substantial portion of the company's assets or revenues are derived from
one or more utilities. Securities in which the series invests are not
selected based upon what sector of the utilities industry a company is in
(i.e., electric, gas, telecommunications) or upon a company's geographic
region. Companies in the utilities industry include:

o companies engaged in the manufacture, production, generation,
transmission, sale or distribution of electric, gas or other types of
energy, water or other sanitary services; and

o companies engaged in telecommunications, including telephone, cellular
telephone, telegraph, satellite, microwave, cable television and other
communications media (but not companies engaged in public broadcasting).

The series is a non-diversified mutual fund. This means that the series may
invest a relatively high percentage of its assets in one or a few issuers.

Equity Investments. MFS uses a bottom-up, as opposed to a top-down,
investment style in managing the equity-oriented funds (including the
equity portion of the series) it advises. This means that securities are
selected based upon fundamental analysis performed by the series' portfolio
manager and MFS' large group of equity research analysts. In performing
this analysis and selecting securities for the series, MFS places
particular emphasis on each of the following factors:

o the current regulatory environment;

o the strength of the company's management team; and

o the company's growth prospects and valuation relative to its long-term
potential.

Equity securities purchased by the series consist of common stocks,
preferred stocks, convertible securities and depositary receipts. Equity
securities may be listed on a securities exchange or traded in the
over-the-counter markets.

o a fixed income stream, and

o the opportunity, through its conversion feature, to participate in an
increase in the market price of the underlying common stock.

Fixed Income Investments. The series invests in securities which pay a
fixed interest rate. These securities include:

o corporate bonds, which are bonds or other debt obligations issued by
corporations or similar entities, including lower rated bonds, commonly
known as junk bonds, which are bonds assigned low credit ratings by
credit rating agencies or which are unrated and considered by MFS to be
comparable in quality to lower rated bonds;

o mortgage-backed securities and asset-backed securities, which are
securities that represent interests in a pool of assets such as mortgage
loans, car loan receivables, or credit card receivables. These
investments entitle the series to a share of the principal and interest
payments made on the underlying mortgage, car loan, or credit card. For
example, if the series invested in a pool that included your mortgage
loan, a share of the principal and interest payments on your mortgage
would pass to the series; and

11
<PAGE>

This three-month "horizon" outlook is used by the portfolio manager(s) of
MFS' fixed-income oriented series (including the fixed-income portion of
the series) as a tool in making or adjusting a series' asset allocations to
various segments of the fixed income markets. In assessing the credit
quality of fixed-income securities, MFS does not rely solely on the credit
ratings assigned by credit rating agencies, but rather performs its own
independent credit analysis.

Foreign Securities. The series invests in foreign securities such as:

o equity securities of foreign companies in the utilities industry,

o fixed income securities of foreign companies in the utilities industry,
and

o fixed income securities issued by foreign governments.

These investments may expose the series to foreign currencies.

> Principal Risks

The principal risks of investing in the series are:

o Concentration: The series' investment performance will be closely tied to
the performance of utility companies. Many utility companies, especially
electric and gas and other energy related utility companies, are subject
to various uncertainties, including:

> risks of increases in fuel and other operating costs;

> restrictions on operations and increased costs and delays as a result
of environmental and nuclear safety regulations;

> coping with the general effects of energy conservation;

> technological innovations which may render existing plants, equipment
or products obsolete;

> the potential impact of natural or man-made disasters;

> difficulty obtaining adequate returns on invested capital, even if
frequent rate increases are approved by public service commissions;

> the high cost of obtaining financing during periods of inflation;

> difficulties of the capital markets in absorbing utility debt and
equity securities; and

> increased competition.

Furthermore, there are uncertainties resulting from certain
telecommunications companies' diversification into new domestic and
international businesses as well as agreements by many such companies
linking future rate increases to inflation or other factors not directly
related to the active operating profits of the enterprise. Because utility
companies are faced with the same obstacles, issues and regulatory burdens,
their securities may react similarly and more in unison to these or other
market conditions. These price movements may have a larger impact on the
series than on a series with a more broadly diversified portfolio.

o Regulation: The value of utility company securities may decline because
governmental regulation controlling the utilities industry can change.
This regulation may prevent or delay the utility company from passing
along cost increases to its customers. Furthermore, regulatory
authorities may not grant future rate increases. Any increases granted
may not be adequate to permit the payment of dividends on common stocks.

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market conditions
or disappointing earnings results.

12
<PAGE>

o Maturity Risk: Interest rate risk will affect the price of a fixed income
security more if the security has a longer maturity because changes in
interest rates are increasingly difficult to predict over longer periods
of time. Fixed income securities with longer maturities will therefore be
more volatile than other fixed income securities with shorter maturities.
Conversely, fixed income securities with shorter maturities will be less
volatile but generally provide lower returns than fixed income securities
with longer maturities. The average maturity of the series' fixed income
investments will affect the volatility of the series' share price.

o Mortgage-Backed and Asset-Backed Securities Risk

> Maturity Risk:

+ When interest rates fall, homeowners are more likely to prepay
their mortgage loans. An increased rate of prepayments on the
series' mortgage-backed securities will result in an unforeseen
loss of interest income to the series as the series may be required
to reinvest assets at a lower interest rate. Because prepayments
increase when interest rates fall, the prices of mortgage-backed
securities do not increase as much as other fixed income securities
when interest rates fall.

+ Asset-Backed Securities: Asset-backed securities have prepayment
risks similar to mortgage-backed securities.

> Enforcing legal rights may be difficult, costly and slow in foreign
countries, and there may be special problems enforcing claims against
foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there may be
less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S. markets.

13
<PAGE>

o Non-Diversified Status Risk: Because the series may invest a higher
percentage of its assets in a small number of issuers, the series is more
susceptible to any single economic, political or regulatory event
affecting those issuers than is a diversified fund.

o As with any mutual fund, you could lose money on your investment in the
series.

An investment in the series is not a bank deposit and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other
government agency.

> Bar Chart and Performance Table

Bar Chart

The bar chart shows changes in the annual total returns of the series'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[bar chart]
1996 18.51%
1997 31.70%
1998 18.06%

During the period shown in the bar chart, the highest quarterly return was
12.01% (for the calendar quarter ended December 31, 1996) and the lowest
quarterly return was (3.79)% (for the calendar quarter ended September 30,
1998).

14
<PAGE>

Performance Table

This table shows how the average annual total returns of the series' shares
compares to a broad measure of market performance and assumes the
reinvestment of distributions.

Average Annual Total Returns as of December 31, 1998
.........................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Utilities Series* 18.06% 25.40%
Standard & Poor's Utility Index+** 14.77% 18.29%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations on January 3, 1995, through December 31, 1998.
+ Source: Lipper Analytical Services, Inc. "Life" refers to the period
from February 1, 1995 through December 31, 1998.
** The Standard & Poor's Utilities Index is a broad based, unmanaged,
market-capitalization-weighted, total return index of all utility
stocks in the Standard & Poor's 500 Composite Index, a broad based
index of common stock total return peformance.

> Portfolio Manager

Maura A. Shaughnessy, a Senior Vice President of the Adviser, has been
employed by the Adviser as a portfolio manager since 1991. Ms. Shaughnessy
has been the series' portfolio manager since its inception.

15
<PAGE>

III CERTAIN INVESTMENT STRATEGIES AND RISKS

Each series may depart from its principal investment strategies by
temporarily investing for defensive purposes when adverse market, economic
or political conditions exist. While a series invests defensively, it may
not be able to pursue its investment objective. A series defensive
investment policy may not be effective in protecting its value.

Each series may engage in active and frequent trading to achieve its
principal investment strategies. This may result in the realization and
distribution to shareholders of higher capital gains. Frequent trading also
increases transaction costs, which could detract from the series'
performance.

Each series may invest in various types of securities and engage in various
investment techniques and practices which are not the principal focus of
the series and therefore are not described in this Prospectus. The types of
securities and investment techniques and practices in which a series may
engage, including the principal investment techniques and practices
described above, are identified in Appendix A to this Prospectus, and are
discussed, together with their risks, in the trust's Statement of
Additional Information (referred to as the SAI), which you may obtain by
contacting MFS Service Center, Inc. (see back cover for address and phone
number).

IV MANAGEMENT OF THE SERIES

> Investment Adviser

Massachusetts Financial Services Company (referred to as MFS or the
adviser) is the investment adviser to each series. MFS is America's oldest
mutual fund organization. MFS and its predecessor organizations have a
history of money management dating from 1924 and the founding of the first
mutual fund, Massachusetts Investors Trust. Net assets under the management
of the MFS organization were approximately $102.9 billion on behalf of
approximately 3.8 million investor accounts as of January 31, 1999. As of
such date, the MFS organization managed approximately $73.6 billion of net
assets in equity fund and equity portfolios. Approximately $4.7 billion of
the assets managed by MFS are invested in securities of foreign issuers and
foreign denominated securities of U.S. issuers. MFS is located at 500
Boylston Street, Boston, Massachusetts 02116.

MFS provides investment management and related administrative services and
facilities to each series, including portfolio management and trade
execution. For these services each series pays MFS an annual management fee
as set forth in the Expense Summary.

MFS or its affiliates generally pay an administrative service fee to
insurance companies which use the series as underlying investment vehicles
for their variable annuity and variable life insurance contracts based upon
the aggregate net assets of the series attributable to these contracts.
These fees are not paid by the series, their shareholders, or by the
contract holders.

> Administrator

MFS provides each series with certain financial, legal, compliance,
shareholder communications and other administrative services. MFS is
reimbursed by each series for a portion of the costs it incurs in providing
these services.

> Distributor

MFS Fund Distributors, Inc. (referred to as MFD), a wholly owned subsidiary
of MFS, is the distributor of shares of the series.

> Shareholder Servicing Agent

MFS Service Center, Inc. (referred to as MFSC), a wholly owned subsidiary
of MFS, performs transfer agency and certain other services for each
series, for which it receives compensation from each series.

V DESCRIPTION OF SHARES

The trust offers shares of each of its series to separate accounts
established by insurance companies in order to serve as investment vehicles
for variable annuity and variable life insurance contracts. The trust also
offers shares of each of its series to qualified pension and retirement
plans. All purchases, redemptions and exchanges of shares are made through
these insurance company separate accounts and plans, which are the record
owner of the shares. Contract holders and plan beneficiaries seeking to
purchase, redeem or exchange interests in the trust's shares should consult
with the insurance company which issued their contracts or their plan
sponsor.

16
<PAGE>

VI OTHER INFORMATION

> Pricing of Series' Shares

The price of each series' shares is based on its net asset value. The net
asset value of each series' shares is determined at the close of regular
trading each day that the New York Stock Exchange is open for trading
(generally, 4:00 p.m., Eastern time) (referred to as the valuation time).
To determine net asset value, each series values its assets at current
market values, or at fair value as determined by the Adviser under the
direction of the Board of Trustees that oversees the series if current
market values are unavailable. Fair value pricing may be used by a series
when current market values are unavailable or when an event occurs after
the close of the exchange on which the series' portfolio securities are
principally traded that is likely to have changed the value of the
securities. The use of fair value pricing by a series may cause the net
asset value of its shares to differ significantly from the net asset value
that would be calculated using current market values.

Insurance companies and plan sponsors are the designees of the trust for
receipt of purchase, exchange and redemption orders from contractholders
and plan beneficiaries. An order submitted to the trust's designee by the
valuation time will receive the net asset value next calculated; provided
that the trust receives notice of the order generally by 9:30 a.m. eastern
time on the next day on which the New York Stock Exchange is open for
trading.

Certain series invest in securities which are primarily listed on foreign
exchanges that trade on weekends and other days when the series does not
price its shares. Therefore, the value of these series' shares may change
on days when you will not be able to purchase or redeem their shares.

> Distributions

Each series intends to pay substantially all of its net income (including
net short-term capital gain) to shareholders as dividends at least
annually. Any realized net capital gains are also distributed at least
annually.

> Tax Considerations

Each series of the trust is treated as a separate entity for federal income
tax purposes. As long as a series qualifies for treatment as a regulated
investment company (which it has in the past and intends to do so in the
future), it pays no federal income tax on the earnings it distributes to
shareholders. In addition, each series also intends to continue to
diversify its assets to satisfy the federal diversification tax rules
applicable to separate accounts that fund variable insurance and annuity
contracts.

Shares of the series are offered to insurance company separate accounts and
qualified pension and retirement plan sponsors. Consult with the insurance
company which issued your contract or your plan sponsor or financial
advisor to understand the federal tax treatment of your investment.

> Right to Reject Purchase and Exchange Orders

Purchases and exchanges should be made for investment purposes only. Each
series reserves the right to reject or restrict any specific purchase or
exchange request. Because an exchange request involves both a request to
redeem shares of one series and to purchase shares of another series, the
series consider the underlying redemption and purchase requests conditioned
upon the acceptance of each of these underlying requests. Therefore, in the
event that the series reject an exchange request, neither the redemption
nor the purchase side of the exchange will be processed.

> Market Timing Policies

The series are not designed for professional market timing organizations or
other entities using programmed or frequent exchanges. The series define a
"market timer" as an individual, or organization acting on behalf of one or
more individuals, if the individual or organization makes during the
calendar year six or more exchange requests among the series.

Accounts under common ownership or control, including accounts administered
by market timers, will be aggregated for purposes of this definition.

The series may impose specific limitations on market timers, including:

o delaying for up to seven days the purchase side of an exchange request by
market timers;

o rejecting or otherwise restricting purchase or exchange requests by
market timers; and

o permitting exchanges by market timers only into certain series.

17
<PAGE>

> In-kind distributions

The series have reserved the right to pay redemption proceeds by a
distribution in-kind of portfolio securities (rather than cash). In the
event that the series makes an in-kind distribution, you could incur the
brokerage and transaction charges when converting the securities to cash.
The series do not expect to make in-kind distributions.

> Unique Nature of Series

MFS may serve as the investment adviser to other funds which have similar
investment goals and principal investment policies and risks to the series,
and which may be managed by the series' portfolio manager(s). While a
series may have many similarities to these other funds, its investment
performance will differ from their investment performance. This is due to a
number of differences between a series and these similar products,
including differences in sales charges, expense ratios and cash flows.

> Year 2000 Readiness Disclosure

The series could be adversely affected if the computer systems used by MFS,
the series' other service providers or the companies in which the series
invests do not properly process date-related information from and after
January 1, 2000 (the "Year 2000 Issue"). MFS recognizes the importance of
the Year 2000 Issue and, to address Year 2000 compliance, created a
separately funded Year 2000 Program Management Office in 1996 comprised of
a specialized staff reporting directly to MFS senior management. The
Office, with the help of external consultants, is responsible for overall
coordination, strategy formulation, communications and issue resolution
with respect to Year 2000 issues. While MFS systems will be tested for Year
2000 readiness before the turn of the century, there are significant
systems interdependencies in the domestic and foreign markets for
securities, the business environments in which companies held by the series
operate and in MFS' own business environment. MFS has been working with the
series' other service providers to identify and respond to potential
problems with respect to Year 2000 readiness and to develop contingency
plans. Year 2000 readiness is also one of the factors considered by MFS in
its ongoing assessment of companies in which the series invests. There can
be no assurance, however, that these steps will be sufficient to avoid any
adverse impact on the series.

> Potential Conflicts

Shares of the series are offered to the separate accounts of insurance
companies that may be affiliated or unaffiliated with MFS and each other
("shared funding") and may serve as the underlying investments for both
variable annuity and variable life insurance contracts ("mixed funding").
Due to differences in tax treatment or other considerations, the interests
of various contract owners might at some time be in conflict. The trust
currently does not foresee any such conflict. Nevertheless, the board of
trustees which oversees the series intends to monitor events in order to
identify any material irreconcilable conflicts which may possibly arise and
to determine what action, if any, should be taken in response. If such a
conflict were to occur, one or more separate accounts of the insurance
companies might be required to withdraw its investments in one or more
series. This might force a series to sell securities at disadvantageous
prices.

VII FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the
series' financial performance for the past 5 years, or, if a series has not
been in operation that long, since the time it commenced investment
operations. Certain information reflects financial results for a single
series' share. The total returns in the table represent the rate by which
an investor would have earned (or lost) on an investment in a series
(assuming reinvestment of all distributions). This information has been
audited by the trust's independent auditors, whose report, together with
the trust's financial statements, are included in the trust's Annual Report
to shareholders. The series' Annual Report is available upon request by
contacting MFSC (see back cover for address and telephone number). These
financial statements are incorporated by reference into the SAI. The
trust's independent auditors are Deloitte & Touche LLP.

18
<PAGE>

1. Capital Opportunities Series
.........................................................................

<TABLE>
<CAPTION>
Period Ended
Year Ended December 31, December 31,
1998 1997 1996*
--------------------------------------------------------------------------------------------------
<S> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ................... $ 11.68 $10.66 $10.00
------- ------ ------
Income from investment operations# --
Net investment income[sec] .............................. $ 0.03 $ 0.12 $ 0.07
Net realized and unrealized gain on investments and
foreign currency ....................................... 3.11 2.66 0.88
------- ------ ------
Total from investment operations ...................... $ 3.14 $ 2.78 $ 0.95
------- ------ ------
Less distributions declared to shareholders --
From net investment income .............................. $ (0.02) $(0.09) $(0.03)
From net realized gain on investments and foreign
currency transactions .................................. (0.01) (1.54) (0.21)
In excess of net realized gain on investments and
foreign currency transactions .......................... -- -- (0.01)
From capital ............................................ -- (0.13) (0.04)
-------- ------- ------
Total distributions declared to shareholders .......... $ (0.03) $(1.76) $(0.29)
-------- ------- ------
Net asset value -- end of period ......................... $ 14.79 $11.68 $10.66
-------- ------- ------
Total return ............................................. 26.80% 26.47% 8.78%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .............................................. 1.02% 1.02% 1.02%+
Net investment income ................................... 0.21% 0.91% 1.72%+
Portfolio turnover ....................................... 144% 270% 44%
Net assets at end of period (000 omitted) ................ $23,908 $5,660 $1,351
</TABLE>

---------
* For the period from the commencement of the series' investment
operations, August 14, 1996, through December 31, 1996.
+ Annualized.
++ Not annualized.
# Per share data are based on average shares outstanding.
## The series has an expense offset arrangement which reduces the series'
custodian fee based upon the amount of cash maintained by the series
with its custodian and dividend disbursing agent. The series' expenses
are calculated without reduction for this expense.
[sec] Subject to reimbursement by the series, the investment adviser agreed
to maintain the expenses of the series, exclusive of management fees,
at not more than 0.25% of average daily net assets. To the extent
actual expenses were over this limitation, the net investment income
(loss) per share and ratios would have been:

<TABLE>
<S> <C> <C> <C>
Net investment income (loss) .......... $0.02 $(0.02) $(0.04)
Ratios (to average net assets):
Expenses## ........................... 1.11% 2.08% 3.83%+
Net investment income (loss) ......... 0.12% (0.18)% (1.09)%+
</TABLE>

19
<PAGE>

2. Research Series
.........................................................................

<TABLE>
<CAPTION>
Period Ended
Year Ended December 31, December 31,
1998 1997 1996 1995*
-------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ................... $ 15.80 $ 13.13 $ 10.89 $10.00
-------- -------- ------- ------
Income from investment operations# --
Net investment income[sec] .............................. $ 0.06 $ 0.05 $ 0.06 $ 0.05
Net realized and unrealized gain on investments and
foreign currency ....................................... 3.59 2.62 2.37 1.01
-------- -------- ------- ------
Total from investment operations ...................... $ 3.65 $ 2.67 $ 2.43 $ 1.06
-------- -------- ------- ------
Less distributions declared to shareholders --
From net investment income .............................. $ (0.03) $ -- $ (0.02) $(0.03)
From net realized gain on investments and foreign
currency transactions .................................. (0.37) -- (0.16) (0.14)
In excess of net realized gain on investments and
foreign currency transactions .......................... -- -- (0.01) --
-------- -------- ------- ------
Total distributions declared to shareholders .......... $ (0.40) $ -- $ (0.19) $(0.17)
-------- -------- ------- ------
Net asset value -- end of period ......................... $ 19.05 $ 15.80 $ 13.13 $10.89
-------- -------- ------- ------
Total return ............................................. 23.39% 20.26% 22.33% 10.62%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .............................................. 0.86% 0.92% 1.01% 1.02%+
Net investment income ................................... 0.33% 0.34% 0.47% 1.15%+
Portfolio turnover ....................................... 83% 99% 56% 28%
Net assets at end of period (000 omitted) ................ $567,778 $285,845 $35,710 $2,530
</TABLE>

---------
* For the period from the commencement of the series' investment
operations, July 26, 1995, through December 31, 1995.
+ Annualized.
++ Not annualized.
# Per share data are based on average shares outstanding.
## The series has an expense offset arrangement which reduces the series'
custodian fee based upon the amount of cash maintained by the series
with its custodian and dividend disbursing agent. The series' expenses
are calculated without reduction for this expense offset arrangement.
[sec] Prior to January 1, 1998, subject to reimbursement by the series, the
investment adviser agreed to maintain expenses of the series, exclusive
of management fees, at not more than 0.25% of average daily net assets.
To the extent actual expenses were over or under this limitation, the
net investment income (loss) per share and the ratios would have been:

<TABLE>
<S> <C> <C> <C> <C>
Net investment income (loss) .......... -- $0.06 $ -- $(0.08)
Ratios (to average net assets):
Expenses## ........................... -- 0.88% 1.48% 3.90%+
Net investment income (loss) ......... -- 0.38% -- (1.73)%+
</TABLE>

20
<PAGE>

3. Total Return Series
.........................................................................

<TABLE>
<CAPTION>
Period Ended
Year Ended December 31, December 31,
1998 1997 1996 1995*
-------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ................... $ 16.63 $ 13.71 $ 12.25 $10.00
-------- ------- ------- ------
Income from investment operations# --
Net investment income[sec] .............................. $ 0.53 $ 0.52 $ 0.46 $ 0.41
Net realized and unrealized gain on investments and
foreign currency ....................................... 1.49 2.40 1.30 2.32
-------- ------- ------- ------
Total from investment operations ...................... $ 2.02 $ 2.92 $ 1.76 $ 2.73
-------- ------- ------- ------
Less distributions declared to shareholders --
From net investment income .............................. $ (0.24) $ -- $ (0.21) $(0.25)
From net realized gain on investments and foreign
currency transactions .................................. (0.29) -- (0.09) (0.23)
-------- ------- -------- ------
Total distributions declared to shareholders .......... $ (0.53) $ -- $ (0.30) $(0.48)
-------- ------- -------- ------
Net asset value -- end of period ......................... $ 18.12 $ 16.63 $ 13.71 $12.25
-------- ------- -------- ------
Total return ............................................. 12.33% 21.30% 14.37% 27.34%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .............................................. 1.00% 1.00% 1.00% 1.00%+
Net investment income ................................... 3.05% 3.25% 3.59% 3.83%+
Portfolio turnover ....................................... 100% 93% 76% 16%
Net assets at end of period (000 omitted) ................ $171,182 $75,612 $19,250 $2,797
</TABLE>

---------
* For the period from the commencement of the series' investment
operations, January 3, 1995, through December 31, 1995.
+ Annualized.
++ Not annualized.
# Per share data are based on average shares outstanding.
## The series has an expense offset arrangement which reduces the series'
custodian fee based upon the amount of cash maintained by the series
with its custodian and dividend disbursing agent. The series' expenses
are calculated without reduction for this expense.
[sec] Subject to reimbursement by the series, the investment adviser
voluntarily agreed to maintain the expenses of the series, exclusive of
management fees, at not more than 0.25% of average daily net assets. To
the extent actual expenses were over/under this limitation, the net
investment income per share and the ratios would have been:

<TABLE>
<S> <C> <C> <C> <C>
Net investment income .......... $0.54 $0.52 $0.32 $0.22
Ratios (to average net assets):
Expenses## .................... 0.91% 1.02% 2.10% 2.49%+
Net investment income ......... 3.14% 3.23% 2.49% 2.09%+
</TABLE>

21
<PAGE>

4. Utilities Series
.........................................................................

<TABLE>
<CAPTION>
Period Ended
Year Ended December 31, December 31,
1998 1997 1996 1995*
-----------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Per share data (for a share outstanding throughout each
period):
Net asset value -- beginning of period ................. $ 17.99 $ 13.66 $12.57 $10.00
------- ------- ------ ------
Income from investment operations# --
Net investment income[sec] ............................ $ 0.46 $ 0.44 $ 0.55 $ 0.39
Net realized and unrealized gain on investments and
foreign currency ..................................... 2.68 3.89 1.78 3.00
------- ------- ------ ------
Total from investment operations .................... $ 3.14 $ 4.33 $ 2.33 $ 3.39
------- ------- ------ ------
Less distributions declared to shareholders --
From net investment income ............................ $ (0.24) $ -- $(0.35) $(0.24)
From net realized gain on investments and foreign
currency transactions ................................ (1.07) -- (0.88) (0.58)
In excess of net realized gain on investments and
foreign currency transactions ........................ -- -- (0.01) --
------- ------- ------ ------
Total distributions declared to shareholders ........ $ (1.31) $ -- $(1.24) $(0.82)
------- ------- ------ ------
Net asset value -- end of period ....................... $ 19.82 $ 17.99 $13.66 $12.57
------- ------- ------ ------
Total return ........................................... 18.06% 31.70% 18.51% 33.94%++
Ratios (to average net assets)/
Supplemental data[sec]:
Expenses## ............................................ 1.01% 1.00% 1.00% 1.00%+
Net investment income ................................. 2.48% 2.92% 4.19% 3.66%+
Portfolio turnover ..................................... 133% 69% 121% 94%
Net assets at end of period (000 omitted) .............. $81,726 $30,147 $9,572 $2,373
</TABLE>

---------
* For the period from the commencement of the series' investment
operations, January 3, 1995, through December 31, 1995.
+ Annualized.
++ Not annualized.
# Per share data are based on average shares outstanding.
## The series has an expense offset arrangement which reduces the series'
custodian fee based upon the amount of cash maintained by the series
with its custodian and dividend disbursing agent. For fiscal years
ending after September 1, 1995, the series' expenses are calculated
without reduction for this expense offset arrangement.
[sec] Subject to reimbursement by the series, the investment adviser agreed
to maintain expenses of the series, exclusive of management fees, at
not more than 0.25% of average daily net assets. To the extent actual
expenses were over/under this limitation, the net investment income per
share and the ratios would have been:

<TABLE>
<S> <C> <C> <C> <C>
Net investment income .......... $0.47 $0.41 $0.32 $0.17
Ratios (to average net assets):
Expenses## .................... 0.98% 1.20% 2.75% 3.08%+
Net investment income ......... 2.51% 2.71% 2.44% 1.62%+
</TABLE>

22
<PAGE>

Appendix A Capital Opportunities Series

> Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Capital
Opportunities Series may engage in the following investment techniques and
practices, which are described, together with their risks, in the SAI.
Investment techniques and practices which are the principal focus of the
series are also described in the Risk Return Summary of the Prospectus.

Symbols [check mark] permitted -- not permitted
--------------------------------------------------------------------------

<TABLE>
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass --
Pass-Through Securities
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities [check mark]
Loans and Other Direct Indebtedness --
Lower Rated Bonds [check mark]
Municipal Bonds --
Speculative Bonds [check mark]
U.S. Government Securities [check mark]
Variable and Floating Rate Obligations [check mark]
Zero Coupon Bonds, Deferred Interest Bonds and PIK [check mark]
Bonds
Equity Securities [check mark]
Foreign Securities Exposure
Brady Bonds [check mark]
Depositary Receipts [check mark]
Dollar-Denominated Foreign Debt Securities --
Emerging Markets [check mark]
Foreign Securities [check mark]
Forward Contracts [check mark]
Futures Contracts [check mark]
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End Funds [check mark]
Closed-End Funds [check mark]
Lending of Portfolio Securities [check mark]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies [check mark]
Options on Futures Contracts [check mark]
Options on Securities [check mark]
Options on Stock Indices [check mark]
Reset Options --
"Yield Curve" Options --
Repurchase Agreements [check mark]
Restricted Securities [check mark]
Short Sales --
Short Sales Against the Box [check mark]
Short Term Instruments [check mark]
Swaps and Related Derivative Instruments --
Temporary Borrowings [check mark]
Temporary Defensive Positions [check mark]
Warrants [check mark]
"When-Issued" Securities [check mark]
</TABLE>

*May be changed only with shareholder approval.

A-1
<PAGE>

Appendix A Research Series

> Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Research
Series may engage in the following investment techniques and practices,
which are described, together with their risks, in the SAI. Investment
techniques and practices which are the principal focus of the series are
also described in the Risk Return Summary of the Prospectus.

Symbols [check mark] permitted -- not permitted
--------------------------------------------------------------------------

<TABLE>
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass --
Pass-Through Securities
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities [check mark]
Loans and Other Direct Indebtedness --
Lower Rated Bonds [check mark]
Municipal Bonds --
Speculative Bonds [check mark]
U.S. Government Securities [check mark]
Variable and Floating Rate Obligations [check mark]
Zero Coupon Bonds, Deferred Interest Bonds and PIK --
Bonds
Equity Securities [check mark]
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts [check mark]
Dollar-Denominated Foreign Debt Securities [check mark]
Emerging Markets [check mark]
Foreign Securities [check mark]
Forward Contracts [check mark]
Futures Contracts --
Indexed Securities/Structured Products [check mark]
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End Funds [check mark]
Closed-End Funds [check mark]
Lending of Portfolio Securities [check mark]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies --
Options on Futures Contracts --
Options on Securities --
Options on Stock Indices --
Reset Options --
"Yield Curve" Options --
Repurchase Agreements [check mark]
Restricted Securities [check mark]
Short Sales --
Short Sales Against the Box --
Short Term Instruments [check mark]
Swaps and Related Derivative Instruments --
Temporary Borrowings [check mark]
Temporary Defensive Positions [check mark]
Warrants [check mark]
"When-Issued" Securities --
</TABLE>

*May be changed only with shareholder approval.

A-2
<PAGE>

Appendix A Total Return Series

> Investment Techniques and Practices

In pursuing its investment objectives and investment policies, the Total
Return Series may engage in the following investment techniques and
practices, which are described, together with their risks, in the SAI.
Investment techniques and practices which are the principal focus of the
series are also described in the Risk Return Summary of the Prospectus.

Symbols [check mark] permitted -- not permitted
--------------------------------------------------------------------------

<TABLE>
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass [check mark]
Pass-Through Securities
Corporate Asset-Backed Securities [check mark]
Mortgage Pass-Through Securities [check mark]
Stripped Mortgage-Backed Securities [check mark]
Corporate Securities [check mark]
Loans and Other Direct Indebtedness [check mark]
Lower Rated Bonds [check mark]
Municipal Bonds [check mark]
Speculative Bonds [check mark]
U.S. Government Securities [check mark]
Variable and Floating Rate Obligations [check mark]
Zero Coupon Bonds, Deferred Interest Bonds and PIK [check mark]
Bonds
Equity Securities [check mark]
Foreign Securities Exposure
Brady Bonds [check mark]
Depositary Receipts [check mark]
Dollar-Denominated Foreign Debt Securities [check mark]
Emerging Markets [check mark]
Foreign Securities [check mark]
Forward Contracts [check mark]
Futures Contracts [check mark]
Indexed Securities/Structured Products [check mark]
Inverse Floating Rate Obligations [check mark]
Investment in Other Investment Companies
Open-End Funds [check mark]
Closed-End Funds [check mark]
Lending of Portfolio Securities [check mark]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions *
Reverse Repurchase Agreements *
Options
Options on Foreign Currencies [check mark]
Options on Futures Contracts [check mark]
Options on Securities [check mark]
Options on Stock Indices [check mark]
Reset Options [check mark]
"Yield Curve" Options [check mark]
Repurchase Agreements [check mark]
Restricted Securities [check mark]
Short Sales --
Short Sales Against the Box --
Short Term Instruments [check mark]
Swaps and Related Derivative Instruments [check mark]
Temporary Borrowings [check mark]
Temporary Defensive Positions [check mark]
Warrants [check mark]
"When-Issued" Securities [check mark]
</TABLE>

*May be changed only with shareholder approval.

A-3
<PAGE>

Appendix A Utilities Series

> Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Utilities
Series may engage in the following investment techniques and practices,
which are described, together with their risks, in the SAI. Investment
techniques and practices which are the principal focus of the series are
also described in the Risk Return Summary of the Prospectus.

Symbols [check mark] permitted -- not permitted
--------------------------------------------------------------------------

<TABLE>
<S> <C>
Debt Securities
Asset-Backed Securities [check mark]
Collateralized Mortgage Obligations and Multiclass [check mark]
Pass-Through Securities
Corporate Asset-Backed Securities [check mark]
Mortgage Pass-Through Securities [check mark]
Stripped Mortgage-Backed Securities --
Corporate Securities [check mark]
Loans and Other Direct Indebtedness --
Lower Rated Bonds [check mark]
Municipal Bonds [check mark]
Speculative Bonds [check mark]
U.S. Government Securities [check mark]
Variable and Floating Rate Obligations [check mark]
Zero Coupon Bonds, Deferred Interest Bonds and PIK [check mark]
Bonds
Equity Securities [check mark]
Foreign Securities Exposure
Brady Bonds [check mark]
Depositary Receipts [check mark]
Dollar-Denominated Foreign Debt Securities [check mark]
Emerging Markets [check mark]
Foreign Securities [check mark]
Forward Contracts [check mark]
Futures Contracts [check mark]
Indexed Securities/Structured Products [check mark]
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End [check mark]
Closed-End [check mark]
Lending of Portfolio Securities [check mark]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions *
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies [check mark]
Options on Futures Contracts [check mark]
Options on Securities [check mark]
Options on Stock Indices [check mark]
Reset Options --
"Yield Curve" Options --
Repurchase Agreements [check mark]
Restricted Securities [check mark]
Short Sales --
Short Sales Against the Box --
Short Term Instruments [check mark]
Swaps and Related Derivative Instruments --
Temporary Borrowings [check mark]
Temporary Defensive Positions [check mark]
Warrants [check mark]
"When-Issued" Securities [check mark]
</TABLE>

*May be changed only with shareholder approval.

A-4
<PAGE>

MFS(R) VARIABLE INSURANCE TRUST(SM)

If you want more information about the trust and its series, the following
documents are available free upon request:

Annual/Semiannual Reports. These reports contain information about the
series' actual investments. Annual reports discuss the effect of recent
market conditions and the series' investment strategy on the series'
performance during its last fiscal year.

Statement of Additional Information (SAI). The SAI, dated May 1, 1999,
provides more detailed information about the trust and its series and is
incorporated into this prospectus by reference.

You can get free copies of the annual/semiannual reports, the SAI and other
information about the trust and its series, and make inquiries about the
trust and its series, by contacting:

MFS Service Center, Inc.
2 Avenue de Lafayette
Boston, MA 02111-1738
Telephone: 1-800-343-2829, ext. 3500
Internet: http://www.mfs.com

Information about the trust and its series (including its prospectus, SAI
and shareholder reports) can be reviewed and copied at the:

Public Reference Room
Securities and Exchange Commission
Washington, D.C., 20549-6009

Information on the operation of the Public Reference Room may be obtained
by calling the Commission at 1-800-SEC-0330. Reports and other information
about the trust and its series are available on the Commission's Internet
website at http://www.sec.gov, and copies of this information may be
obtained, upon payment of a duplicating fee, by writing the Public
Reference Section at the above address.

The trust's Investment Company Act file number is 811-8326

MSG 11/98 224M 90/290/390/890