1st LD Writethru: U.S. stocks narrowly mixed ahead of Yellen testimony

U.S. stocks ended mixed Monday, with the Nasdaq Composite Index extending its gains into a ninth straight day, as investors shifted their focus from Greek debt concerns to Federal Reserve Chair Janet Yellen's remarks in the next two days.

The Dow Jones Industrial Average shed 23.60 points, or 0.13 percent, to 18,116.84. The S&P 500 edged down 0.64 point, or 0.03 percent, to 2,109.66. The Nasdaq added 5.01 points, or 0.10 percent, to 4,960.97.

Greece won some breathing space after a bridge agreement was reached Friday with its eurozone creditors. The deal averted an imminent Grexit, but more tough challenges lie ahead. Greece must present a list of reform proposals on Monday to secure the financial lifeline.

Wall Street was keeping a watchful eye on Yellen's semi-annual testimony to Congress Tuesday and Wednesday. Although many consider last week's Fed minutes as dovish, some analysts believe Yellen is likely to imply that a June rate hike is still on the table.

"We expect she will stick to the message of the Fed statement -- which is, after all, the heart of the belief of the Federal Open Market Committee -- but will use ideas from the minutes for nuance, " said Chris Low, chief economist at FTN Financial, in a note.

On the economic front, U.S. existing-home sales declined in January to their lowest rate in nine months, said the National Association of Realtors on Monday. Total existing-home sales fell 4.9 percent to a seasonally adjusted annual rate of 4.82 million in January from an upwardly-revised 5.07 million in December.

In corporate news, Apple Inc. announced a plan to spend 1.9 billion U.S. dollars to build two new European data centers, with one in Ireland, and the other in Denmark. The plan is the tech giant's largest investment ever. Its shares gained 2.71 percent to 133.00 dollars apiece Monday.

Shares of HSBC dropped 4.28 percent to 44.68 dollars apiece after the Europe's biggest bank reported its profit before tax for 2014 was 18.7 billion dollars, down 17 percent from 2013.

Boeing shares also dipped 2.26 percent to 154.74 dollars apiece after Goldman Sachs downgraded the airplane manufacturer to "sell" from "neutral," citing that the demand equation for aircraft could worsen.

U.S. stocks surged Friday, with both the Dow Jones Industrial Average and the S&P 500 refreshing their record highs, as the eurozone and Greece reached the agreement over a four-month extension to its bailout. Endite