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* Reports Q1 net sales in line with forecasts
* Data shows WPP winning most U.S. work
* Shares slip in weak market
* Sorrell defends 70 mln stg pay packet (Adds details on pay)
By Kate Holton
LONDON, April 28 (Reuters) - Britain's WPP, theworld's biggest advertising company, enjoyed a solid first threemonths to the year after it outperformed rivals in securing awave of contracts up for grabs in the United States.
An unprecedented number of U.S. blue-chip companies have puttheir contracts up for review in the past year, re-thinkingwhich agencies they want for marketing advice and trying todrive down the prices they pay.
Nicknamed "reviewageddon", analysts estimate that more than$25 billion in spending on advertising was put up for review in2015, a record for the industry which grew up from the 1920s onthe New York street of Madison Avenue.
In the first quarter of 2016, WPP's agencies either won orretained contracts from fast food chain Wendy's, e-commercecompany Jet.com and retailer Target in North America.
Data from research company Recma and cited by WPP in presenting its results on Thursday showed the firm had eitherwon or retained the most contracts put out for review by bluechip firms which are generally in a cautious mood at the moment.
While U.S. rivals Omnicom and Interpublic also gained new work, the Paris-based Publicis appeared to suffer the most according to the data.
"We've been the best performing agency," WPP's high-profilechief executive Martin Sorrell told Reuters. "This tsunami hashappened over the last year, it's starting to ease but it'sstill there."
The performance of WPP, which has grown from a two-personoperation in the London area of Lincoln's Inn Fields, has helpedSorrell to earn a 70 million pound ($102 million) package,making him the best paid boss on the FTSE 100 Index.
According to the Recma graph, WPP won or retained nearly $7billion of work during the wave of reviews, while Publicis lostmore than $3 billion. The rest of the spoils were shared betweenOmnicom, Interpublic and Dentsu.
The strong performance helped WPP to report first-quarterlike-for-like net sales growth of 3.2 percent, in line withforecasts and putting it on track for its full-year target.
Its shares slipped 1 percent, in line with a drop of thewider FTSE 100.
SOLID PERFORMANCE
The update from WPP echoed similar performances from itsrivals which have reported solid trading helped by buoyantdemand in North America, where events such as the U.S.presidential election plus business connected to the Olympicgames in Brazil have boosted demand.
Despite the review setback for Publicis, Brian Wieser, ananalyst at Pivotal Research Group, said its numbers had beenboosted by revenue from those clients which have alreadyannounced plans to change agencies, but have not yet completedthe transition. Its digital business also improved.
Analysts said the growth at WPP had been driven by NorthAmerica, which makes up 39 percent of revenue, and digital.
"We continue to believe that WPP remains best-positionedstrategically vs. peers and their long-term growth shouldslightly outperform given the company's business and countrymix," said Wieser.
WPP's performance should help Sorrell when he appears beforea potentially fractious annual general meeting in June whereinvestors will vote on his pay package.
Sorrell, who has run WPP for more than 30 years, said hisremuneration was linked to the firm's performance. He alsorejected suggestions from a BBC Radio interviewer that he shouldbe embarrassed by the scale of his pay.
"I'm not embarrassed about the growth of the company fromtwo people in one room in Lincoln's Inn Fields in 1985 to190,000 people in 112 countries and a leadership position in ourindustry.
"They (the shareholders) will vote as they see fit."
($1 = 0.6864 pounds) (Reporting by Kate Holton; editing by David Clarke, Sarah Youngand David Stamp)
