* S&P 500 less than 1 percent from record levels
* Hillshire to buy Pinnacle Foods for $6.6 billion
* Ukraine situation remains in focus after referendum
* Indexes up: Dow 0.6 pct, S&P 0.7 pct, Nasdaq 1.2 pct (Updates to market open)
By Ryan Vlastelica
NEW YORK, May 12 (Reuters) - U.S. stocks rose on Monday, with the Dow hitting another all-time high and the S&P 500 moving within 1 percent of its own record.
Gains were broad, with nine of the 10 primary S&P 500 sectors in positive territory. About 78 percent of stocks traded on the New York Stock Exchange rose on the day while more than three-fourths of Nasdaq-listed stocks gained.
The advance game despite ongoing geopolitical concerns in the Ukraine after pro-Russian rebels voted in favor of self-rule in eastern regions of the country in a referendum dismissed by Kiev and Western governments as illegal. Separately, the European Union is set to step up pressure on Russia by taking steps to extend sanctions to companies, as well as individuals.
"The vote seemed like a negative, but the violence that many thought would happen didn't, and at this point no news is good news when it comes to Ukraine," said Channing Smith, co-portfolio manager of the Capital Advisors Growth Fund at Capital Advisors in Tulsa, Oklahoma.
Internet and biotech names were among the strongest advancers of the day. Biogen Idec gained 2.9 percent to $294.92 while TripAdvisor Inc was up 2.9 percent to $87.07. Both sectors - often described as "momentum" stocks due to massive gains in recent months - have been wildly volatile in recent sessions, moving on both concerns over valuation and hopes for high levels of growth.
The Dow Jones industrial average was up 97.13 points, or 0.59 percent, at 16,680.47. The Standard & Poor's 500 Index was up 12.91 points, or 0.69 percent, at 1,891.39. The Nasdaq Composite Index was up 47.31 points, or 1.16 percent, at 4,119.18.
The S&P 500 is 0.3 percent from a record intraday high reached on April 4. The Russell 2000 index of small-cap stocks rose 1.3 percent. Last week, it flirted with correction territory, dropping nearly 10 percent from its all-time closing high.
"It will be interesting to see whether we can hold above 1,900 on the S&P, since lately we've retreated anytime we near that level," Smith said. "Our trading range has been very narrow, with early rallies fading and early losses getting bought."
Hillshire Brands Co agreed to buy Pinnacle Foods Inc for about $6.6 billion. Pinnacle jumped 15 percent to $34.94 while Hillshire fell 5.6 percent to $34.88.
Tesaro Inc jumped 17 percent to $28.13 after the company said its experimental drug for the prevention of chemotherapy-induced nausea and vomiting met the main goal in a third late-stage trial. (Editing by Bernadette Baum)