* Amazon shares touch life high after revenue beats estimates
* Comcast drops plan to merge Time Warner Cable
* Xerox slumps as it cuts forecast
* Dow flat, S&P up 0.1 pct, Nasdaq up 0.6 pct (Updates to open)
By Tanya Agrawal
April 24 (Reuters) - Wall Street opened up on Friday as strong results from tech behemoths Google, Amazon and Microsoft set the Nasdaq Composite on track to extend its record close set the previous session.
Amazon shares soared as much as 15.6 percent to a lifetime high of $451 after the e-commerce company's revenue came in above estimates on Thursday.
Google gained 2.8 percent to $573.15 after reporting higher quarterly revenue and profit and Microsoft added 6.6 percent to $46.22 after it topped Wall Street estimates.
The Nasdaq Composite closed at 5,056.06 on Thursday, surpassing its record set in March 2000, just before the dot-com bubble burst.
"I think we're on more solid footing than the last time," said Gordon Charlop, managing director at Rosenblatt Securities in New York, talking about the Nasdaq's highs.
"There could be some vulnerability in some of the tech names, given the change in the value of the dollar, but I don't get the same sense that we're overvalued at these levels the way we were the last time we got here."
At 10:15 a.m. EDT (1415 GMT) the Dow Jones industrial average was down 4.27 points, or 0.02 percent, at 18,054.42, the S&P 500 was up 2.59 points, or 0.12 percent, at 2,115.52 and the Nasdaq Composite was higher 30.85 points, or 0.61 percent, at 5,086.91.
Comcast abandoned its proposed $45 billion merger with Time Warner Cable after U.S. regulators said the deal would give Comcast an unfair advantage in the Internet-based services market. Time Warner rose 2.7 percent to $152.75 and Comcast was little changed.
Xerox shares slumped 9.2 percent $11.91 after it cut its 2015 profit forecast, adding to a growing list of companies that have blamed a strong U.S. currency for weakened results or forecasts.
Of the 169 companies in the S&P 500 that have reported results so far, 71 percent have exceeded earnings expectations but only 44 percent have beaten on revenue.
Declining issues outnumbered advancing ones on the NYSE by 1,454 to 1,296, for a 1.12-to-1 ratio on the downside; on the Nasdaq, 1,380 issues fell and 1,030 advanced for a 1.34-to-1 ratio favoring decliners.
The benchmark S&P 500 index was posting 12 new 52-week highs and no new lows; the Nasdaq Composite was recording 58 new highs and 10 new lows. (Editing by Savio D'Souza and Rodrigo Campos)