The Federal Reserve’s latest take on the US economy put many investors into sell mode yesterday, sending stocks mostly lower after a brief upward turn early in the day.

Fed Chair Janet Yellen, speaking before Congress, said the US economy has yet to recover fully, but raised the possibility the central bank could raise its key short-term interest rate sooner than currently projected.

The Fed also issued a report noting that valuations for stocks in some sectors, such as social media and biotech firms, appear to be stretched, sending shares in Facebook, Twitter and LinkedIn lower.

By suggesting some stocks could be overvalued, the Fed is adding to a growing belief among some market watchers that stocks are due for a pullback, said Drew Wilson, an equity analyst at Fenimore Asset Management.

“In this type of environment when you have a lot of uncertainty, essentially you have this equilibrium that’s looking to be broken one way or another, and the Fed chair saying ‘financial bubble’ could do that,” Wilson said.

Investors had plenty more to consider, including a mostly encouraging batch of corporate earnings and economic data.

The major US financial market indexes were up slightly in premarket trading as JPMorgan, Goldman Sachs and Johnson & Johnson released quarterly results that exceeded Wall Street’s expectations.

Separate reports on US retail sales and manufacturing growth also gave the market an early lift.

But stock indexes diverged shortly after the market opened and then fully veered into the red about an hour into regular trading as investors began to tune into Yellen delivering the central bank’s semi-annual economic report to Congress.

Stocks finished the day mixed, with the Dow Jones industrial average eking out a tiny gain on the day.

The Dow added 5.26 points, or 0.03 per cent, to 17,060.68. The index is down slightly from its July 3 record of 17,068.65.

The Standard & Poor’s 500 index fell 3.82 points, or 0.2 per cent, to 1,973.28. The index is down 0.6 per cent from its most recent all-time high of 1,985.44 set July 3.

The Nasdaq composite shed 24.03 points, or 0.5 per cent, to 4,416.39.

The three stock indexes are all up for the year.

Bond prices barely budged. The yield on the 10-year Treasury note held steady at 2.55 per cent.

Yellen told Congress that the Fed intends to keep providing significant support to the US economy to boost growth and improve labor market conditions, noting that the economic recovery is not yet complete.

Employers added 288,000 jobs last month, the fifth straight month of gains above 200,000. The national unemployment rate has slid to 6.1 percent, a 5 1/2-year low.

Yellen noted that if labor market conditions continue to improve more quickly than anticipated, the Fed could raise its key short-term interest rate sooner than currently projected.

“In light of corporate earnings being good, retail sales being good, manufacturing being good, even a data-driven Fed chairman is going to have to raise rates earlier than the market really wants,” said Doug Cote, chief market strategist at Voya Investment Management. “So all the good fundamental data that should be good for the markets is also hawkish for rates.”

Beyond the Fed, investors are mostly focused on company earnings this week, including quarterly reports from Bank of America, eBay and Yum Brands on Wednesday.

Bank earnings set a good tone for the latest earnings season.

JPMorgan, the nation’s largest bank by assets, said its second-quarter earnings fell nine per cent as revenue at its investment banking and mortgage businesses dropped. The stock gained US$1.98, or 3.5 per cent, to US$58.27. Goldman’s profit rose five per cent, helped by record results from investment banking. Goldman gained US$2.17, or 1.3 per cent, to US$169.17.

Investors hammered companies whose quarterly results were less positive.

Shares in rent-to-own retailer Aaron’s tumbled 9.5 per cent after the company cut its profit and revenue outlook for the second quarter, partly citing performance of its core business. The stock shed US$3.19 to US$30.34.