Briefly

Tax-free money market fund yields, always volatile, have plunged in the last week as new cash inflows to the funds caused more bidding for short-term municipal IOUs by fund managers, said fund tracker IMoneyNet.com. The average seven-day compound yield on tax-exempt funds slumped to 3.84% this week from 4.61% a week earlier. Meanwhile, the average yield on taxable money funds rose to 5.85% from 5.70% a week ago, a nine-year high, in the wake of the Federal Reserve’s half-point boost in its key short-term interest rate May 16. . . .

Single-stock futures contracts may not be in our near future, after all: The Securities and Exchange Commission, which favors allowing such futures, said Wednesday that it hasn’t been able to iron out disagreements about the contracts with the Commodity Futures Trading Commission. That could hold up a broader overhaul of U.S. futures laws. . . . Optimism over U.S. stocks is falling among independent investment newsletter writers. A weekly poll by Investors Intelligence showed the bulls at 46% now, the lowest this year. But “contrarian” investors may view that as a sure sign the market will rally.