* Casino stocks dip, while gunmakers rise after Las Vegas shooting
* U.S. factory activity surge to a more than 13-yr high in Sept
* Indexes up: Dow 0.42 pct, S&P 0.23 pct, Nasdaq 0.08 pct (Updates stock prices)
By Ankur Banerjee and Gayathree Ganesan
Oct 2 (Reuters) - The S&P 500 and the Dow traded just below record highs touched at open on Monday, in a strong start to the fourth quarter, boosted by financials and healthcare stocks and after data pointed to underlying strength in the economy.
The tech-heavy Nasdaq slipped briefly to negative territory after hitting an all-time high earlier.
Shares of casino operators were lower, while those of gunmakers moved higher after a gunman killed at least 50 people in Las Vegas on Sunday in the largest mass shooting in U.S. history.
U.S. factory activity surged to a more than 13-year high in September amid strong gains in new orders and raw material prices, according to the Institute for Supply Management. Construction spending rose 0.5 percent to $1.21 trillion in August, adding to the robust economic data.
Dollar extended gains after the data. The currency has been rising after Fed Chair Janet Yellen's recent speech that suggested the odds of an interest rate hike in December remain high.
Meanwhile, President Donald Trump met with former Federal Reserve Governor Kevin Warsh and three others to become the new chief of the U.S. central bank and promised a decision this month.
Investors have also pinned hopes on Trump's tax reform plan, which envisages lowering corporate tax to 20 percent.
"There is a sense of optimism that something will get done on corporate tax reform now that healthcare has been finally put to bed, if you will," said Nadia Lovell, US Equity Strategist, J.P. Morgan Private Bank.
"The fact is that you're also seeing a proposal to include a reduction of individual tax rates ... so we think that the consumer will have more dollars to put to work in the economy."
Eight of the 11 major S&P indexes were positive on Monday, driven by gains in healthcare and financials.
Boosting the broader index was Johnson & Johnson, Gilead Sciences among healthcare stocks and JP Morgan and Citigroup among financials.
But the gains were tempered by a drop in energy and late-losses in techs.
The energy sector was down 0.75 pct, led by decline in Exxon Mobil. A rise in U.S. drilling and higher OPEC output put brakes on a rally that helped oil prices register their biggest third-quarter gain in 13 years.
Investors' are now likely to turn their attention to third-quarter corporate earnings. Earnings for the third-quarter are expected to increase 6.2 percent from a year earlier, according to Thomson Reuters research.
"I think it is the earnings ... you've seen a pretty healthy first half of the year with earnings, when we (are) headed into Q3, there is a sense of optimism that you can see upfront," Lovell said.
At 12:37 a.m. ET, the Dow Jones industrial average was up 94.88 points, or 0.42 percent, at 22,499.97, the S&P 500 was up 5.76 points, or 0.23 percent, at 2,525.12.
The Nasdaq Composite was up 5.27 points, or 0.08 percent, at 6,501.23.
General Motors hit record high after brokerage Deutsche Bank said the carmaker could launch driverless cars on a large scale in 2020.
Shares of Nordstrom fell 5 percent following a New York Post report that talks to take the department store operator private were faltering, dragging down rivals' shares.
Advancing issues outnumbered decliners on the NYSE by 1,772 to 1,056. On the Nasdaq, 1,844 issues rose and 1,015 fell. (Reporting by Ankur Banerjee, Gayathree Ganesan and Yashaswini Swamynathan in Bengaluru; Editing by Sriraj Kalluvila)