U.S. stocks notched a second straight advance with a turnaround so furious it’s been seen only a half dozen times during the bull run. The bad news: It’s not necessarily a sign the latest turmoil is over.

The S&P 500 erased a loss of almost 2% to eke out a gain, one day after its futures contract staged a similar rebound overnight. The cash index has produced such reversals five other times since the bull market began in 2009 and three of them foreshadowed more pain to come.

The impressive recovery for equities defied an easy explanation. Some investors cited a drop in U.S. Treasury yields so severe that it made stocks a relative bargain. Others pointed to the market ructions as clinching further Federal Reserve easing, while some said the 6.5% drop over six days through Monday simply went too far too quickly.

Whatever the catalyst, a look at the past to huge moves that have characterized August trading so far normally happen in clusters. Deciphering whether this latest reversal marked an end is trickier. When the S&P 500 last undid a slump of at least 2% in one day, it marked the end of a rout last December that nearly ended the bull market. In February 2018, a single day of euphoria gave way to pain that persisted another two months.

“Chasing the price action, if anything, is a very dangerous way to look at markets. This is the type of trading typically seen in a very volatile environment,” Michael O’Rourke, JonesTrading’s chief market strategist, said by phone. “It’s easy to get burned.”

Stocks started the day lower after investors grew concerned that the global economy stood on the precipice of a recession after unexpected easings at central banks in New Zealand, Thailand and India. The cuts sparked a torrid rally in sovereign bonds, sinking U.S. Treasury rates to multiyear lows.

“We would be reluctant to say the worst is over,” said Ernie Cecilia, chief investment officer at Bryn Mawr Trust Co. “It’s late in the game, we’re in the 11th year of the economic cycle, economic growth is not even. The bond market thinks the Fed’s wrong, there’s no question about that.”

—With assistance from Vildana Hajric.