<PAGE>
MFS(R) UNION STANDARD(R) EQUITY FUND
Supplement dated February 1, 2000 as revised July 21, 2000
to the Current Prospectus
This Supplement describes the fund's class I shares, and it supplements certain
information in the fund's Prospectus dated February 1, 2000. The caption
headings used in this Supplement correspond with the caption headings used in
the Prospectus.
You may purchase class I shares only if you are an eligible institutional
investor, as described under the caption "Description of Share Classes" below.
1. EXPENSE SUMMARY
Expense Table. The "Expense Table" describes the fees and expenses that you
may pay when you buy, redeem and hold shares of the fund. The table is
supplemented as follows:
<TABLE>
<CAPTION>
<S> <C>
Class I
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage
of offering price).................................................................... None
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase
price or redemption proceeds, whichever is less)...................................... None
</TABLE>
Annual Fund Operating Expenses (expenses that are deducted from fund
assets):
<TABLE>
<CAPTION>
<S> <C>
Management Fees 0.65%
Distribution and Service (12b-1) Fees................................................... None
Other Expenses(1) 0.30%
-----
Total Annual Fund Operating Expenses(1)................................................. 0.95%
Fee Waiver and/or Expense Reimbursement(2).......................................... (0.09)%
-------
Net Expenses 0.86%
</TABLE>
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(1) The fund has an expense offset arrangement which reduces the fund's
custodian fee based upon the amount of cash maintained by the fund with
its custodian and dividend disbursing agent. The fund may enter into
other similar arrangements and directed brokerage arrangements, which
would also have the effect of reducing the fund's expenses. Any such fee
reductions are not reflected in the table. Had these fee reductions been
taken into account, "Net Expenses" would be 0.85%.
(2) MFS has contractually agreed to bear the fund's expenses such that "Other
Expenses", after taking into account the expense offset arrangement
described above, do not exceed 0.20% annually. These contractual fee
arrangements will continue until at least February 1, 2001, unless
changed by the board of trustees which oversees the fund.
2. EXAMPLE OF EXPENSES
The "Example of Expenses" table is intended to help you compare the cost of
investing in the fund with the cost of investing in other mutual funds.
These examples assume that:
o You invest $10,000 in the fund 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 fund's operating expenses remain the same, except that the
fund's total operating expenses are assumed to be the fund's "Net
Expenses" for the first year, and the fund's "Total Annual Fund
Operating Expenses" for subsequent years (see the table above).
The table is supplemented as follows:
Share Class Year 1 Year 3 Year 5 Year 10
------ ------ ------ -------
Class I shares $97 $283 $486 $1,069
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3. DESCRIPTIONS OF SHARE CLASSES
The "Description of Share Classes" is supplemented as follows:
If you are an eligible institutional investor (as described below), you may
purchase class I shares at net asset value without an initial sales charge or
CDSC upon redemption. Class I shares do not have annual distribution and service
fees, and do not convert to any other class of shares of the fund.
The following eligible institutional investors may purchase class I shares:
o certain retirement plans established for the benefit of employees
of MFS and employees of MFS' affiliates;
o any fund distributed by MFD, if the fund seeks to achieve its
investment objective by investing primarily in shares of the fund
and other MFS funds:
o any retirement plan, endowment or foundation which:
has, at the time of purchase of class I shares, aggregate
assets of at least $100 million, and
invests at least $10 million in class I shares of the fund
either alone or in combination with investments in class I
shares of other MFS Funds (additional investments may be
made in any amount).
MFD may accept purchases from smaller plans, endowments or
foundations or in smaller amounts if it believes, in its sole
discretion, that such entity's aggregate assets will equal or
exceed $100 million, or that such entity will make additional
investments which will cause its total investment to equal or
exceed $10 million, within a reasonable period of time;
o bank trust departments or law firms acting as trustee or manager
for trust accounts which, on behalf of their clients (i) initially
invest at least $100,000 in class I shares of the fund or (ii)
have, at the time of purchase of class I shares, aggregate assets
of at least $10 million invested in class I shares of the fund
either alone or in combination with investments in class I shares
of other MFS Funds. MFD may accept purchases that do not meet
these dollar qualification requirements if it believes, in its
sole discretion, that these requirements will be met within a
reasonable period of time. Additional investments may be made in
any amount; and
o certain retirement plans offered, administered or sponsored by
insurance companies, provided that these plans and insurance
companies meet certain criteria established by MFD from time to
time.
4. HOW TO PURCHASE, EXCHANGE AND REDEEM SHARES
The discussion of "How to Purchase, Exchange and Redeem Shares" is supplemented
as follows:
You may purchase, redeem and exchange class I shares only through your MFD
representative or by contacting MFSC (see the back cover of the Prospectus for
address and phone number). You may exchange your class I shares for class I
shares of another MFS Fund (if you are eligible to purchase them) and for shares
of the MFS Money Market Fund at net asset value.
<PAGE>
5. FINANCIAL HIGHLIGHTS
The "Financial Highlights" table is intended to help you understand the fund's
financial performance. It is supplemented as follows:
Financial Statements - Class I shares
<TABLE>
<CAPTION>
<S> <C> <C> <C> <C> <C>
Year Year Year Year Year
Ended Ended Ended Ended Ended
9/30/99 9/30/98 9/30/97 9/30/96 9/30/95
------- ------- ------- ------- -------
Per share data (for a share outstanding throughout each period):
Net asset value - beginning of period $ 16.96 $ 16.43 $ 13.85 $ 11.85 $ 9.64
------- ------- ------- ------- -------
Income from investment operations# -
Net investment incomess. $ 0.16 $ 0.16 $ 0.17 $ 0.18 $ 0.17
Net realized and unrealized gain on investments 0.88 1.94 4.01 2.25 2.14
-------- -------- -------- -------- ---------
Total from investment operations $ 1.04 $ 2.10 $ 4.18 $ 2.43 $ 2.31
-------- -------- --------
Less distributions declared to shareholders -
From net investment income $ (0.15) $ (0.18) $ (0.19) $ (0.15) $ (0.10)
From net realized gain on investments (1.38) (1.39) (1.41) (0.28) --
--------- --------- --------- ---------- -----
Total distributions declared to shareholders $ (1.53) $ (1.57) $ (1.60) $ (0.43) $ (0.10)
--------- --------- --------- ---------
Net asset value - end of period $ 16.47 $ 16.96 $ 16.43 $ 13.85 $ 11.85
------- ------- ------- -------
Total return 5.97% 13.74% 32.51% 20.96% 24.21%
Ratios (to average net assets)/Supplemental datass.:
Expenses## 0.86% 0.86% 0.98% 1.01% 1.03%
Net investment income 0.90% 0.95% 1.12% 1.36% 1.58%
Portfolio turnover 58% 43% 49% 81% 125%
Net assets at end of period (000 omitted) $85,880 $76,408 $68,527 $49,318 $35,842
</TABLE>
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ss. Effective February 1, 1997, subject to reimbursement, the Fund pays MFS a
fee not greater than 0.20% of average daily net assets pursuant to a
temporary expense arrangement in which MFS has voluntarily agreed to pay
all of the Fund's operating expenses, exclusive of management fees. Prior
to February 1, 1997, the investment adviser agreed to maintain the
expenses of the Fund at not more than 1.00% of average daily net assets.
To the extent actual expenses were over this limitation, the net
investment income per share and the ratios would have been:
<TABLE>
<CAPTION>
<S> <C> <C> <C> <C> <C>
Net investment income $ 0.14 $ 0.14 $ 0.15 $ 0.18 $ 0.16
Ratios (to average net assets):
Expenses## 0.95% 0.97% 1.11% 1.03% 1.12%
Net investment income 0.81% 0.83% 0.98% 1.33% 1.49%
</TABLE>
# Per share data are based on average shares outstanding.
## Ratios do not reflect expense reductions from certain expense offset
arrangements.
The date of this Supplement is February 1, 2000 as revised July 21, 2000.
