* Merck to buy Idenix, Analog to buy Hittite
* Apple sees heavy trading following stock split
* CBOE Volatility index near lowest since Feb '07
* Dow, S&P 500 and Nasdaq all up 0.1 pct (Updates to open)
NEW YORK, June 9 (Reuters) - U.S. stocks advanced on Monday, boosted by a number of major acquisition deals, though gains were slight with key indexes continuing to hover around records.
If the S&P 500 ends higher on Monday, that will mark its 11th rise of the past 13 sessions, and its seventh record close of the past eight trading days. While Wall Street's upward trend looks intact, traders may need new catalysts to bid the market up further lest the momentum runs out of steam.
Market participants will continue to watch the CBOE Volatility index, which rose 3.5 percent. On Friday, the "fear index" fell to its lowest level since February 2007. It remains nearly half of its historical average, which some analysts worry is a signal that the market is not fully accounting for issues that could derail the rally.
"I don't think you can argue that the market is stretched. There's room for the economy to grow, and while the VIX may suggest some complacency, I don't see the kind of euphoria that would indicate over-optimism about stocks," said Rex Macey, who helps oversee $20 billion in assets as chief investment officer at Wilmington Trust in Atlanta, Georgia. "I would be careful about pulling back on stocks too soon."
Merck & Co agreed to buy Idenix Pharmaceuticals Inc in a deal valued at about $3.85 billion, while Analog Devices Inc said it would buy Hittite Microwave Corp in a deal valued at $2 billion.
Separately, Tyson Foods Inc prevailed over Pilgrim's Pride Corp in a bidding war over Hillshire Brands Co , offering to buy the company for $8.55 billion including debt.
Shares of Idenix more than tripled, jumping 231 percent to $23.95 on heavy volume, while Hittite gained 28 percent to $77.75; Hillshire rose 4.8 percent to $61.76. Merck dipped 0.8 percent to $57.40 while Analog was up 6.1 percent at $55.93 and Tyson fell 2.6 percent to $39.08.
The Dow Jones industrial average rose 9.96 points, or 0.06 percent, to 16,934.24, the S&P 500 gained 1.69 points, or 0.09 percent, to 1,951.13 and the Nasdaq Composite added 6.14 points, or 0.14 percent, to 4,327.54.
Apple Inc was the Nasdaq's most active name, rising 0.2 percent to $92.40 in heavy volume in the tech titan's first session after a seven-for-one stock split. Separately, the Nikkei on Friday reported that Apple was preparing to sell its first wearable device in October, aiming to produce 3 million to 5 million smartwatches a month in its initial run.
Family Dollar Stores Inc jumped 16 percent to $70.25 as the S&P's biggest percentage gainer after hedge fund billionaire Carl Icahn late Friday reported a 9.39 percent stake in the company, making him the discount retailer's largest shareholder. Dollar General Corp surged 11 percent to $64.23.
(Editing by Bernadette Baum)