Federal Reserve Chair Jerome Powell is making investors jittery, according to JPMorgan Chase & Co. (JPM).

In a research note, reported on by CNBC and MarketWatch, analysts claimed that the stock market suffered losses of around $1.5 trillion in market cap following speeches from the Fed’s top boss. (See also: Who Is Jerome Powell?)

Powell has hosted three news conferences after Federal Open Market Committee meetings since taking over as chair in February. According to JPMorgan, the S&P 500, tracked by exchange-traded funds like SPDR S&P 500 ETF (SPY), iShares Core S&P 500 ETF (IVV) and Vanguard S&P 500 ETF (VOO), fell by roughly 0.44 percentage point each time he held one those conferences.

Marko Kolanovic, the brokerage’s global head of quantitative and derivatives strategy, noted that Powell’s congressional testimony and other speeches also had a similarly negative impact on the stock market. On five out of nine occasions that he spoke, the S&P fell 500 by 0.4 percentage point on average, the analyst claimed, meaning that Powell has so far cost stock market investors $1.5 trillion.

Kolanovic and his peers believe that the pattern of Powell speeches causing market sentiment to retreat suggests that investors have little faith in the Fed and its chair’s understanding of the current landscape.

"Specifically, the equity market likely implies that the Fed is underestimating various risks, and hence is increasing the implied probability of the Fed committing a policy error in the future," Kolanovic wrote in the report. "A higher probability of a policy error translates into lower equity prices on the news."

JPMorgan provided some examples of unpopular remarks made by Powell, including his comments that stocks are overvalued, that multiple rate hikes are needed or necessary, and that a stock market "sell-off warrants attention if sustained." Analysts added that these remarks imply that the Fed doesn't understand market structure and may stay on the sidelines too long. (See also: How Do Interest Rates Affect the Stock Market?)

Powell is due to make more public appearances in 2019, hosting news conferences after every meeting rather than just quarterly. Investors will be hoping that the he is able to exude more positivity as his schedule increases. Failing that, short-sellers could look to profit from this trend.