(Bloomberg) -- Traders are accustomed to a bumpy ride whenever Jerome Powell speaks. But when Powell speaks at the same time Janet Yellen is talking to Congress about the health of the banking sector, the turbulence can get overwhelming.

That’s what happened Wednesday afternoon as the back half of the Federal Reserve chairman’s press conference overlapped with the Treasury Secretary’s appearance before a Senate subcommittee. The S&P 500 fell, rose, went back to unchanged then plunged again as traders tried to synthesize comments on the health of the economy, rates trajectory, the state of banks and how far the government will go to protect depositors.

It’s rare that two people of such stature speak at the same time, worse when they project messages that traders interpreted as in opposition. A little while after hearing what they thought was Powell tipping broader protection to depositors should financial stress spread, Yellen came on the feed to knock the hope down. The S&P 500 erased an earlier gain of 0.9%, marking the sixth time this year that an intraday rally of that size was reversed. 

“It’s astounding that Yellen and Powell would have given contradictory messages on bank deposits at the same time,” said Steve Chiavarone, senior portfolio manager and head of multi-asset solutions at Federated Hermes. “Powell essentially said that all deposits are safe, Yellen said, ‘Hold my beer.’ You would have thought that they would have coordinated.”

Asked about a broad increase in deposit insurance, Yellen said that it was “not something that we have looked at. It is not something we are considering.” That happened right around 3 p.m. in New York, after Powell said that the banking system was sound. Yet some argued that his insistence that the Fed would continue to raise rates higher than expected if it sees the need to do so also helped push stocks lower. 

Traders noted that bank stocks took the brunt of the pain following Yellen’s comments. The SPDR S&P Bank ETF (ticker KRE), which tracks regional banks in the US, fell 5.7%. 

“Her comments clearly affected bank stocks negatively, but her comments roughly coincided with Powell’s comments that they will continue to do what take to fight inflation, including raising rates more than anticipated,” said Steve Sosnick, chief strategist at Interactive Brokers. “It’s tough to untangle them.”

In the days leading up to the Federal Open Market Committee release, investors were in disagreement over how the central bank was going to move, with economists at some of the biggest banks saying it wasn’t going to raise rates at all. But the Fed hiked for a ninth straight meeting and said there could be more raises to come.

The FOMC voted unanimously to increase its target for the federal funds rate by a quarter percentage point to a range of 4.75% to 5%, the highest since September 2007. 

Read more: Powell Stresses Commitment to Cooling Prices as Fed Hikes Rates

But both Powell and Yellen are trying to thread the needle between causing more havoc while also saying the government will cover any private risk, says Mike Bailey, director of research at FBB Capital Partners.

“Unfortunately, investors were walking on eggshells before the Powell and Yellen comments and the dueling messages are leaving investors in a state of confusion, as seen in the drop in the S&P,” Bailey said.

Pinpointing exactly what’s moving the market on a minute-to-minute basis is an inexact science at the best of times. Doing it when two of the most important people in finance are speaking on dueling streams is an enterprise that is in most respects doomed to futility. In the end, Wednesday’s verdict on Powell and Yellen’s stereo address was a negative one. The S&P 500 tumbled 1.7% for its worst fall in two weeks.

On the other hand, it’s still up for the week.

--With assistance from Lu Wang and Emily Graffeo.

(Adds chart after fourth paragraph. A previous version of this story was corrected.)

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