(Reuters) – The S&P 500 and the Nasdaq retreated on Tuesday as Federal Reserve Chair Jerome Powell warned the U.S. economic recovery remained far from complete, with a selloff in some of the biggest technology companies also weighing on sentiment.

The domestic rebound could still slip into a downward spiral if the coronavirus is not effectively controlled and growth sustained, Powell said.

“Markets are worried about what the Fed knows that we don’t know,” said John Augustine, chief investment officer at Huntington National Bank in Columbus, Ohio.

“The things that are obvious to us are that small businesses are closing and unemployment remains high in the services sector. The Fed aggressively wants to address both of those with more fiscal stimulus.”

Comments from officials that a stimulus deal was still possible had lifted the three main stock indexes on Monday, helping them recoup losses from last week that were sparked by news that President Donald Trump had contracted COVID-19.

Trump said on Tuesday he felt “real good” upon returning to the White House after a three-day hospital stay where he received an experimental treatment for the disease.

Six of the 11 major S&P sectors were up, with the battered energy index <.SPNY> tracking a 2% jump in oil prices.

A rotation into value-linked sectors <.IVX> such as industrials <.SPLRCI> helped boost the blue-chip Dow, but the Nasdaq slipped further away from record highs following a dip in shares of heavyweight technology mega-caps.

Amazon.com Inc <AMZN.O>, Apple Inc <AAPL.O>, Facebook Inc <FB.O> and Google-owner Alphabet Inc <GOOGL.O> fell between 0.8% and 1.6% after news about a U.S. House of Representatives’ antitrust report containing a “thinly veiled call to break up” the companies.

Declines in their share prices led the S&P 500 growth index <.IGX> down 0.4%.

“When you’re in bubble territory with higher volatility, the market is very much driven by sentiment,” said Matt Hanna, portfolio manager at Summit Global Investments.

“The sentiment has shifted a little bit, it’s not nearly as bullish as it was just a couple months ago.”

At 12:37 p.m. ET, the Dow Jones Industrial Average <.DJI> was up 0.10%, the S&P 500 <.SPX> was down 0.06%, and the Nasdaq Composite <.IXIC> was down 0.26%.

A 1.2% jump helped the S&P banking subindex <.SPXBK> outperform the benchmark index as U.S. long-dated Treasury yields climbed to four-month peaks.

Boeing Co <BA.N> fell 3.0% after the planemaker cut its rolling 20-year forecast for airplane demand due to the fallout from the COVID-19 pandemic.

U.S.-listed shares of BioNTech <BNTX.O> jumped 8.0% after the European health regulator said it had started a real-time review of the COVID-19 vaccine being developed by the German biotech firm and U.S. drugmaker Pfizer Inc <PFE.N>. Pfizer’s shares dipped 0.1%.

Shares of audio device makers Sonos Inc <SONO.O> and Logitech <LOGN.S> fell 6.8% and 5.1%, respectively, after their speakers were removed from Apple’s online stores.

Advancing issues outnumbered decliners almost 2-to-1 on the NYSE and the Nasdaq.

The S&P index recorded 25 new 52-week highs and no new low, while the Nasdaq recorded 97 new highs and nine new lows.

(Reporting by Devik Jain and Sagarika Jaisinghani in Bengaluru; Additional reporting by Sinead Carew in New York; Editing by Shounak Dasgupta and Maju Samuel)