Even with worries about an impending recession, investors have been surprisingly upbeat on the days when the Fed has increased interest rates.

Investors were unhappy. On Sept. 21, just minutes after the Federal Reserve raised interest rates for the fifth consecutive time, the S&P 500 shed 1.6%. Were the markets in free fall? No, the index started rising. 30 minutes later the index jumped to session highs. What changed? Did investors suddenly become satisfied with the Fed’s inflation-fighting actions? No, it started falling, again. In just over an hour, the S&P 500 fell from its peak to close at the lowest point of the day. Had the Fed gone too far this time? Would the 0.75 percentage point increase spark a recession and lower corporate profits?

The tension of that September afternoon hasn’t dissipated as the Federal Reserve Board meets again this week. The central bank is widely expected to raise interest rates by another 0.75 percentage point on Wednesday. Where markets will move after this week’s announcement is anyone’s guess. But the stock market’s response to the last five rate hikes may provide some clues. Despite concerns that the Fed’s aggressive interest rate hikes could send the economy into a recession, the S&P 500 rose more than 1% on all but one of the days when the Fed announced rate increases.

Although it was the only down day of the bunch, perhaps the most relevant stock market response was September’s, which brought the federal funds range above 3%. With another 0.75 percentage point increase on Wednesday, the range will touch 4% for the first time since 2008.