We had an interesting situation on Thursday in which both the price of the S&P 500 Index (SPY) and the ten-year Treasury yield hit 40 day highs during the session. Rising rates have been the bane of many a bull market, but how have they affected prices recently?I went back to 2004 (N = 819 trading days) and examined what happened in the S&P 500 Index following rising vs. falling 40-day periods in the 10-year yield. When the yield has been up over the past 40 days (N = 398), the next 40 days in SPY have averaged a gain of only .12% (206 up, 192 down).When 40-day yields have fallen (N = 421), the next 40 days in SPY have averaged a healthy gain of ...