Congress is attempting to eliminate several popular tax strategies so Wall Street investment managers are urging clients to act quickly. Many tax-saving techniques may be curbed if some in congress have their way.

Advisers are betting that any legislation enacted later this year won't affect certain deals completed prior to congressional-committee actions, expected in mid-July at the earliest. Thus,"we're racing" to wrap up transactions now, one Wall Street executive says.

Among the techniques that may be killed is one designed to defer and reduce taxes on income from hedge funds and similar types of investments. Instead of investing directly in a fund, the investor buys a derivative whose return is tied to the fund's performance. This transforms what would otherwise be short-term capital gains and ordinary income, taxed as high as 39.6% at the federal level, into long-term capital gains, typically taxed at a top rate of 20%.