<PAGE>
MFS(R) Union Standard(R) Equity Fund
Supplement to the Current Prospectus
The section of the prospectus entitled "Information Concerning Shares of
the Fund/Redemptions and Repurchases" is amended by adding the following
language after the paragraph entitled "Reinstatement Privilege" on page 27:
In-Kind-Distributions. The MFS Funds have reserved the right to pay
redemption proceeds by a distribution in-kind of portfolio securities (rather
than cash). In the event that the fund makes an in-kind distribution, you could
incur brokerage and transaction charges when converting the securities to cash.
The fund does not expect to make in-kind distributions, and if it does, the fund
will pay, during any 90-day period, your redemption proceeds in cash up to
either $250,000 or 1% of the fund's net assets, whichever is less.
The date of this Supplement is May 14, 1999.
