Updated from 4:09 p.m.

Stocks ended lower Monday, amid some profit-taking and mixed economic news.

The Dow Jones Industrial Average lost 51 points to 8531, while the Nasdaq lost 1 point to 1504 after being as high as 1519 earlier. The S&P 500 shed 4 points to 926.

"The Nasdaq made a nice move to the upside recently, but there's not a lot to hang your hat on," said Daniel Morgan, fund manager at Noble Financial Group in Florida. "We've yet to see a turnaround in spending, and the economy hasn't shown enough strength to support that."

First-quarter earnings rose about 14% for the S&P 500 companies that reported results in the past few weeks, according to Thomson First Call. Among those companies, 62% beat analysts' estimates, 20% reported earnings in line with expectations and 18% missed forecasts, according to the latest report by Ehrenkrantz King Nussbaum.

On the economic front, the Institute for Supply Management released data on the service sector for April, showing that the industry expanded following a contraction in March. The index rose to 50.7 last month from 47.9 the prior month. But on a down note, job cuts in U.S. corporations in April rose 71% to 146,399 from 85,396 in March, the highest level since last November, according a report by the outplacement firm Challenger, Gray & Christmas.

"For the individual investor, it has been a long process: He was in love, got jilted, and now, how do you mend a broken heart?" said Douglas Altabef, market analyst and managing director at Matrix Asset Advisors in New York. "This will culminate with an infatuation when the market can potentially extend a rally, but so much is still perception."

On the NYSE, 1.4 billion shares traded hands, with winners ahead of losers by a margin of about four to three. Some 1.9 billion shares changed hands on the Nasdaq, with advancers outpacing decliners by three to two.

Among tech stocks, investors were bidding up Cisco ( CSCO), which reports fiscal third-quarter earnings Tuesday after the close. Its shares ended the day up 1% at $15.41.

Retailer J.C. Penney ( JCP) predicted its sales will grow as much as 3% in May for the first time this year. The company's shares rose 2% to $17.54.

E-commerce company USA Interactive ( USAI) said it is buying online lender LendingTree ( TREE) for $734 million in a stock deal. USA Interactive shares lost 3% to $34.08, while LendingTree climbed 41% to $20.67.

Texas Instruments ( TXN) affirmed its outlook for second-quarter earnings of 8 cents a share and revenue growth of 7% for the period. The company's shares gained 1% to $19.52.

Meanwhile, Citigroup ( C) said in a Securities and Exchange Commission filing that it is in talks with regulators to settle any wrongdoing involving energy trader Dynegy ( DYN), which last year paid the government $3 million to settle a case concerning accounting fraud. Citigroup shares fell 0.5% to $39.50.

Pfizer ( PFE) climbed 1% to $31.90 after partner German Boehringer Ingelheim said the lung drug that the companies are selling had improved lung function more than rival GlaxoSmithKline's ( GSK) product.

Local and long-distance operator Verizon Communications ( VZ) said it will cut prices by 30% for high-speed Internet service, which could cause a price war and eat into the sector's profits. Verizon shares shed 2% to $37.29.

Cable operator Cox Communications ( COX) said it had a loss in the first quarter, but also reported that it signed up more customers for services such as high-speed Internet. Cox shares closed down 5% at $30.40.

American Airlines' parent, AMR ( AMR), said Friday it expects increased savings after having renegotiated labor contracts. AMR shares gained 13% to $6.19.

Defense contractor Boeing ( BA) reportedly is under government investigation for allegedly using documents from rival Lockheed Martin ( LMT) to win a military contract, The Wall Street Journal reported. Boeing shares ended 4% lower at $27.60.

Meanwhile, Lockheed Martin won a contract worth almost $2 billion to supply 48 F-16 fighters to Poland in what the U.S. Air Force described as the largest arms deal in eastern Europe to date. The company's shares slid 1% to $49.50.

Also in the defense sector, Northrop Grumman ( NOC) said 2003 profit will be within previous estimates. Shares lost 2% to $88.28.

Warren Buffett's Berkshire Hathaway ( BRKa) posted record first-quarter earnings from operations. The stock rose 3% to $72,800. AON ( AON) reported a drop in first-quarter earnings amid higher pension costs. AON shares gained 5% to $23.70.

Treasuries were lower, with the yield on the 10-year note up 8 basis points at 3.92%. Crude oil prices for April delivery were down. The dollar was weaker against the yen and euro.

Overseas markets were higher, with the German DAX up 1.3% at 3024 and Hong Kong's Hang Seng up 1.2% at 8916. Markets in London and Japan were closed for holidays.

The Dow rose 128 points Friday to 8582, while the S&P 500 gained almost 14 points to 930. The Nasdaq gained 30 points to 1502.