* Caterpillar higher after raising forecast for second time
* Alphabet falls after saying costs rising faster than sales
* McDonald's, Biogen rise after quarterly results
* Futures up: Dow 96 pts, S&P 6.5 pts, Nasdaq 5 pts (Adds details, comment, updates prices)
By Tanya Agrawal
July 25 (Reuters) - The S&P and the Dow looked set to open higher on Tuesday, helped by strong earnings from Caterpillar and McDonald's, but Google-parent Alphabet may weigh on the tech-heavy Nasdaq.
Caterpillar's shares rose 5.4 percent in premarket trading after the company reported quarterly results that smashed expectations and raised its full-year outlook for the second time this year.
McDonald's was up 3 percent after reporting a better-than-expected rise in sales.
However, Alphabet fell 2.8 percent, after the tech giant warned that expenses would remain high as more searches shift to mobile devices.
The S&P tech index has been the best performing sector this year and earnings from big tech companies will be closely watched to see if the rally has legs.
Amazon and Facebook report results later this week, while Apple is due to report next week.
The market's run to record highs has left equities relatively expensive and investors are counting on earnings to justify the valuations.
The S&P 500 is trading at around 18 times earnings estimates for the next 12 months, well above their long-term average of 15 times.
Earnings are expected to have climbed 8.8 percent in the second quarter, compared with an 8 percent rise estimated at the start of the month, according to Thomson Reuters I/B/E/S.
This week alone, 190 S&P 500 companies are expected to report quarterly results.
Advanced Micro Devices, AT&T, Chipotle and Chubb are among the major companies that report after the closing bell.
"Investors will have a lot to chew on today as earnings results include at least 12 major companies," said Peter Cardillo, chief market economist at First Standard Financial.
"We look for another mixed session as the FOMC meeting begins and the health care vote comes into play."
Dow e-minis were up 96 points, or 0.45 percent, with 23,225 contracts changing hands at 8:26 a.m. ET (1226 GMT).
S&P 500 e-minis were up 6.5 points, or 0.26 percent, with 124,438 contracts traded.
Nasdaq 100 e-minis were up 5 points, or 0.08 percent, on volume of 21,534 contracts.
The Fed kicks off a two-day meeting later in the day to discuss its monetary stance and the timing of its long-awaited balance sheet reduction.
While no rate hike is expected due to subdued inflation, the central bank's statement on Wednesday will be parsed for clues on the pace of future rate hikes.
Investors will also be keeping an eye on a Senate vote on a healthcare bill, with lawmakers voting on whether to push forward with repealing Obamacare or perhaps abandon it entirely.
Biogen rose 4.4 percent after the biotech company raised its full-year revenue forecast.
Eli Lilly was down 1.5 percent, while 3M fell 2.6 percent after reporting results. (Reporting by Tanya Agrawal in Bengaluru; Editing by Anil D'Silva)