US STOCKS-Wall St flat as Fed still dominates investor sentiment

* Investors uncertain after Fed move

* Starwood up after Marriott's higher offer

* IHS (NYSE: IHS - news) up after deal to buy Markit (NasdaqGS: MRKT - news)

* Valeant rises on search for new CEO; Ackman to join board

* Dow up 0.16 pct, S&P up 0.13 pct, Nasdaq (NasdaqGS: NDAQ - news) up 0.27 pct (Updates to afternoon)

By Laila Kearney

New York, March 21 (Reuters) - Wall Street traded flat on Monday as investors searched for fresh catalysts and grappled with mixed feelings about the U.S (Other OTC: UBGXF - news) . Federal Reserve's dovish move last week that pushed the S&P 500 and Dow into positive territory for the year.

U.S. stocks curved slightly higher by the afternoon after opening lower.

"The market is still digesting the Fed news from last week," said David Carter, chief investment officer at Lenox Wealth Advisors in New York. "While some are saying it's positive, some are concerned it expresses (doubt) about global economic health."

The Fed's decision to cut the number of expected rate hikes this year to two was among several recent measures by central banks to support growth and calm turmoil in global financial markets.

While the U.S. economy could continue to recover moderately, the market would react to negative surprises in European and Chinese data in coming weeks, said Lisa Kopp, head of traditional investments at U.S. Bank Wealth Management in Minneapolis.

The Dow Jones industrial average was up 27.8 points, or 0.16 percent, to 17,630.1, the S&P 500 had gained 2.66 points, or 0.13 percent, to 2,052.24 and the Nasdaq Composite had added 12.95 points, or 0.27 percent, to 4,808.59.

Crude prices edged up as data showed a drawdown at the Cushing, Oklahoma, delivery hub for U.S. crude and ahead of front-month contract expiry in the U.S. crude futures.

Valeant shares were up 7.1 percent to $28.89 after it announced the departure of its chief executive officer and said billionaire investor Bill Ackman had joined its board as it tries to cleans up accounting problems and save its business. . Shares (Berlin: DI6.BE - news) of the beleaguered drugmaker were one of the day's most actively traded.

Apple (LSE: 0R2V.L - news) stock was down 0.2 percent at $105.70. The company unveiled a smaller, cheaper iPhone.

Sherwin-Williams fell 5.6 percent to $272.47 after it agreed to buy rival U.S. paint company Valspar. Valspar shares were up 24.2 percent at $104.14.

Shares of Starwood were up 4.2 percent at $83.94 after the Sheraton hotel owner accepted a higher offer from Marriott that beat an all-cash offer by a group led by China's Anbang Insurance Group. Marriott was down 1.2 percent at $72.30.

IHS was up 8.6 percent at $120.23 after the U.S. business research provider said it would buy London-based Markit in an all-stock deal valued at about $5.9 billion. Markit's Nasdaq-listed shares were up 12.13 percent at $33.07.

Advancing issues outnumbered declining ones on the NYSE by 1,506 to 1,454, for a 1.04-to-1 ratio on the upside; on the Nasdaq, 1,568 issues rose and 1,207 fell for a 1.30-to-1 ratio favoring advancers.

The S&P 500 posted 17 new 52-week highs and no new lows; the Nasdaq recorded 35 new highs and 9 new lows. (Additional reporting by Abhiram Nandakumar in Bengaluru; Editing by Don Sebastian and Nick Zieminski)