US STOCKS-Wall Street edges higher thanks to gain by Apple
* Fed's John Williams sees 2-3 rate hikes in 2016
* Yellen to speak later in the week
* Monsanto jumps after Bayer's $62 bln buyout offer
* Indexes: Dow up 0.27 pct, S&P up 0.09 pct, Nasdaq up 0.29 pct (Updates to afternoon)
By Noel Randewich
May 23 (Reuters) - Wall Street edged higher on Monday as a bounce in Apple helped offset growing concerns that the U.S. Federal Reserve could raise interest rates sooner than later.
The timing of future Fed rate hikes in the face of a sluggish economy is a major focus among stock investors who have benefited from historically low borrowing costs since the 2008 financial crisis.
San Francisco Fed President John Williams and his St. Louis counterpart, James Bullard, both struck hawkish tones in separate appearances on Monday.
Last week, investors were surprised at central bank minutes that opened the door to a rate hike as soon as June. Investors will listen for fresh clues to the Fed's intentions when Chair Janet Yellen speaks on Friday. Continuación...