It appears the Federal Reserve just did one of the best things it could for stocks: doing nothing.

Bespoke Investment Group’s Paul Hickey finds that the S&P 500 rises an average of about 1 percent in the month after a Fed decision to hold interest rates steady.

“It’s almost a corollary to the old phrase ‘never short a dull market.’ Never short a dull Fed either,” the firm’s co-founder told CNBC’s “Trading Nation” on Wednesday, the day the Fed announced its decision not to raise rates. “When you think about it, it makes pretty good sense. If the Fed is doing nothing, it means conditions are pretty good.”

Hickey wrote in a recent research note that “the market loves a Fed on hold,” and he uses this chart to illustrate the pattern:

“The market can steadily rise higher here going forward in the next month — especially given the Fed’s statements that they’re not going to become more aggressive on the tightening policy unless inflation becomes significant and persistent,” said Hickey. “We are a long way from both of those levels right now.”

In situations when the Fed shifts rates in either direction, the S&P 500 typically falls in the four weeks after a decision. Even a rate cut is little guarantee it will set the stage for market gains, according to Hickey.

“If the Fed is hiking rates, it means inflation is running hotter than forecast. Whereas if the Fed is cutting rates, it means that the economy is not doing so well,” he said.

His data goes back to 1994, when the Fed began announcing its rate decision at the conclusion of its meetings.

But with the S&P 500 within 2% from all-time highs, it’s no ordinary market. Plus, the market is dealing with economic fallout from the coronavirus outbreak.

Yet Hickey believes the historical trend is intact as long as the virus doesn’t get much worse.

“We’re not at the stage where we have exuberant sentiment at this point,” Hickey said. “Investors have definitely turned more bullish, but we haven’t quite hit extreme levels.”