US STOCKS-S&P 500 rallies for week on Amazon, Expedia results

* Amazon, Expedia surge after results beat forecasts

* First-quarter U.S. GDP misses forecast

* Procter & Gamble drops after earning

* Indexes up: Dow 0.2 pct, S&P 0.2 pct, Nasdaq 0.6 pct

By Caroline Valetkevitch

NEW YORK, April 27 (Reuters) - U.S. stocks advanced on Friday and posted their best weekly gains in a month as stronger-than-expected earnings from Amazon.com Inc and Expedia Inc reinforced confidence in corporate performance.

Wall Street managed a fourth day of gains as the strong earnings season outweighed a surprisingly weak reading on first-quarter economic growth.

Expedia stock surged 23.5 percent to $40.31 and was the top percentage gainer on Nasdaq, followed by Amazon, which climbed 15.7 percent to $226.85. An S&P retail index rose 3.5 percent and hit an all-time high.

Growth in S&P 500 earnings rose to 7.2 percent this week from 3.2 percent at the start of the month, according to Thomson Reuters data. About 73 percent of the companies that have reported so far have beaten expectations.

"You get this fear coming into the period that corporate earnings are not going to live up to expectations, and we haven't seen it," said Patrick O'Hare chief market analyst for Briefing Research in Chicago.

"The earnings have been better than expected, and a number of companies are calling attention to the continued growth unfolding here in the United States."

The Dow Jones industrial average was up 23.69 points, or 0.18 percent, at 13,228.31. The Standard & Poor's 500 Index was up 3.38 points, or 0.24 percent, at 1,403.36. The Nasdaq Composite Index was up 18.59 points, or 0.61 percent, at 3,069.20.

The S&P 500 posted its best weekly percentage gain since March and the Nasdaq its best gain since February.

Earlier this week, a blowout quarter from Apple Inc gave the Nasdaq its best day of the year .

With one more trading day left in the month, the S&P 500 is slightly lower so far in April but still up 11.6 percent for the year. The S&P is well above its 50-day moving average.

The Commerce Department reported the U.S. economy expanded at a 2.2 percent annual rate in the first quarter, below economists' expectations for growth of 2.5 percent.

On the downside, Procter & Gamble Co shares fell 3.6 percent to $64.44 after it cut its full-year profit view and posted lower earnings.

Starbucks Corp fell 5.3 percent to $57.43 and was one of the biggest percentage decliners on the Nasdaq 100 after it reported results late on Thursday. Investors focused on weakness in European sales, even though its quarterly profit topped estimates.