One Republican sent out a flier this week citing a 3.8-percent increase in the S & P 500 stock index since passage of the tax cuts in May .
One Republican flier cited a 3.8 percent increase in the S & P 500 stock index since passage of the tax cuts in May .
The yield on the benchmark 10-year Treasury note rose as high as 4.66 percent Aug. 14 from 3.07 percent in June .