(Bloomberg) -- U.S. stocks extended losses in after-hours trading after disappointing earnings from tech giants and amid growing concern that equities have become overvalued. The dollar jumped the most since September and Treasury yields slipped.Facebook Inc. and Tesla Inc both fell after reporting results, dragging down ETFs that track major stock gauges. The S&P 500 Index recorded its worst rout since October in the cash session, with the gauge down 2.6% after Federal Reserve officials left their main interest rate unchanged without promising any more aid for the economy. The selloff was widespread, sinking all 11 groups in the benchmark stock gauge.Turmoil continued in pockets of the market where retail traders are becoming a dominant force, with shares of GameStop Corp. and AMC Entertainment Holdings Inc. soaring as investment pros questioned whether there’s any rationale behind the moves.The Stoxx Europe 600 Index declined the most in five weeks as the European Union and AstraZeneca Plc squabbled over vaccine delivery delays. The euro fell after a European Central Bank official said the markets are underestimating the odds of a rate cut. Officials in the U.K. announced new rules to try to curb the spread of Covid-19 and Germany cut its 2021 economic growth forecast to 3% from 4.4%.An extended run higher for stocks has reversed this week as investors look to a spate of earnings releases for clues about the health of the corporate world. Federal Reserve Chairman Jerome Powell said at a press conference that the U.S. economy was a long way from full recovery and still short of policy makers’ inflation and job goals.“It was always doubtful the Fed would announce any new actions this month,” said Seema Shah, chief strategist at Principal Global Investors. “After a few weeks of Fed speakers pushing back on the monetary tightening narrative, it wasn’t surprising to hear Powell reassert the message that tapering is not on the agenda for 2021.”The stock selloff is also being driven partly by speculation that hedge funds will be forced to reduce their equity holdings as retail investors make a concerted effort to boost shares the professional investors have bet against, according to Matt Maley, chief market strategist at Miller Tabak + Co.“A lot of them are getting burned by their shorts, and I think the market is worried that they’ll have to sell some stocks to meet their margin calls,” he said.Elsewhere, Bitcoin fell below $30,000 before paring the decline and precious metals slumped. Asian stocks fell for a second day as investors took a breather following the regional benchmark’s ascent to a record high Monday. In the region, benchmarks in India, Vietnam and the Philippines were among the biggest losers.These are some key events coming up in the week ahead:Apple Inc., Tesla Inc., Facebook Inc. and Samsung Electronics Co. are among companies reporting results.Fourth-quarter GDP, initial jobless claims and new home sales are among U.S. data releases Thursday.U.S. personal income, spending and pending home sales come Friday.These are the main moves in markets:StocksThe S&P 500 Index fell 2.6% as of 4 p.m. New York time.The Stoxx Europe 600 Index declined 1.2%.The MSCI Asia Pacific Index fell 0.8%.The MSCI Emerging Market Index dipped 1.3%.CurrenciesThe Bloomberg Dollar Spot Index rose 0.7%.The euro fell 0.5% to $1.2104.The British pound weakened 0.4% to $1.3683.The Japanese yen fell 0.5% to 104.18 per dollar.BondsThe yield on 10-year Treasuries fell one basis point to 1.02%.Germany’s 10-year yield fell one basis point to -0.55%.Britain’s 10-year yield was little changed at 0.27%.CommoditiesWest Texas Intermediate crude rose 0.1% to $52.67 per barrel.Gold fell 0.5% to $1,842.36 an ounce.For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.