* S&P 500 hits record on merger, acquisition activity
* Insurance stocks rise after Humana comments
* Men's Wearhouse raises offer for Jos. A. Bank
* Indexes up: Dow 0.8 pct, S&P 0.7 pct, Nasdaq 0.8 pct
NEW YORK, Feb 24 (Reuters) - U.S. stocks rose on Monday, advancing in a broad rally as merger activity boosted the S&P 500 to an all-time high.
Despite the day's gains, many investors were concerned that markets were getting overvalued with recent data failing to meet expectations, though the latter has largely been blamed on harsh winter weather rather than worsening fundamentals.
RF Micro Devices Inc agreed to buy TriQuint Semiconductor Inc for about $1.6 billion, while Men's Wearhouse Inc raised its cash tender offer for rival men's clothing retailer Jos. A. Bank Clothiers Inc JOSB.O to $63.50 per share from $57.50.
Shares of RF climbed 15.5 percent to $6.70 while TriQuint gained 20 percent to $11.04. Men's Wearhouse rose 7.7 percent to $48.57 while Jos. A. Bank was up 8.8 percent at $59.89.
"Seeing merger activity is a good sign for a continued growth market, but we've started to taper back our domestic holdings in favor of international markets which seem cheaper given the S&P's (price-to-earnings ratio)," said Paul Radeke, vice president at the Minneapolis-based KDV Wealth Management, which has about $660 million in assets under management.
Monday's deals followed Facebook's massive acquisition of messaging company WhatsApp last week.
Humana Inc and UnitedHealth Group were both among the S&P's biggest percentage gainers, with Humana up 5.5 percent to $109.24 after it said the government's proposed cuts to the private Medicare program appeared less than it had forecast. UnitedHealth rose 3.1 percent to $76.09.
Aetna Inc rose 1.6 percent to $71.52 after giving a 2014 earnings outlook.
The Dow Jones industrial average was up 126.53 points, or 0.79 percent, at 16,229.83. The Standard & Poor's 500 Index was up 13.68 points, or 0.74 percent, at 1,849.93. The Nasdaq Composite Index was up 31.93 points, or 0.75 percent, at 4,295.34.
Nine of the S&P's 10 sectors rose on the day, with energy shares up 1.7 percent following positive comments from KLR Group on Noble Energy, which jumped 4.3 percent to $69.74. More than two-thirds of companies traded on the New York Stock Exchange rose on the day, while 63 percent of Nasdaq-listed companies gained.
Overseas markets remained in focus after Ukrainian President Viktor Yanukovich was ousted following deadly street protests, leaving a potential power vacuum and an ailing economy. Ukraine's finance ministry said the economy required $35 billion in foreign aid over the next two years, with the first tranche needed within two weeks.
While most U.S. companies have limited direct exposure to Ukraine, investors worry that the instability in the region could spread throughout emerging markets.
In the latest U.S. data, the National Activity index fell to -0.39 in January from 0.16 in December while financial data firm Markit's preliminary February read on the services sector fell from 56.7 to 52.7.
Pfizer Inc shares rose 1.4 percent to $31.91 after the company said that its drug Prevenar 13 prevented community-acquired pneumonia in individuals age 65 and older in a study.
Verizon Communications Inc dipped 1.2 percent to $46.70 after the company gave a 2014 revenue outlook.
Many traders are looking ahead to Thursday, when Federal Reserve Chair Janet Yellen will speak to the Senate Banking Committee in her semi-annual testimony about monetary policy.
Yellen's comments will be scoured for insight into the extent to which bad weather has impacted economic activity, as well as for confirmation that the Fed will not make any changes to its schedule for trimming stimulus.