* Big banks due to report results this week
* Qualcomm rises after investors urge spinoff of unit
* Builders FirstSource to buy ProBuild for $1.63 bln
* Indexes up: Dow 0.17 pct, S&P 0.15 pct, Nasdaq 0.45 pct (Updates to open)
By Tanya Agrawal
April 13 (Reuters) - The Dow and S&P 500 were little changed in morning trading on Monday after three straight days of gains as the corporate earnings season was poised to kick into high gear with a slew of reports this week.
Gains on the Nasdaq outpaced the two other major Wall Street indexes, buoyed by gains in Qualcomm, up 1.6 percent at $70.28, and Apple, up 0.8 percent at $128.16.
Activist investor Jana Partners asked chipmaker Qualcomm to consider spinning off its chip unit from its patent-licensing business to boost its sagging stock price.
Analysts said Apple will likely ramp up production of the Apple Watch on strong pre-orders following its launch.
Big banks, including JPMorgan Chase and Bank of America, are due to report results, providing an expected bright spot in an otherwise gloomy first quarter. Profits of companies on the S&P 500 are projected to have declined 2.9 percent in the first three months from a year ago, according to Thomson Reuters data.
The dollar gained 0.3 percent against a basket of major currencies after hitting a peak of 99.99, its highest in four weeks. Market participants have been concerned about the impact of the currency's strength on the profits of multinational companies.
"We had a big move last week and we're heading into earnings season and we've had a few warning signs last week from a couple of companies where the impact of foreign exchange is going to be greater than what was previously thought," said Brian Fenske, head of sales trading at ITG in New York.
Fenske said investors were waiting for results, with many companies giving earnings forecasts for the rest of the year.
The Dow Jones industrial average rose 29.93 points, or 0.17 percent, to 18,087.58, the S&P 500 gained 3.22 points, or 0.15 percent, to 2,105.28 and the Nasdaq Composite added 22.67 points, or 0.45 percent, to 5,018.65.
Builders FirstSource shares soared 58.1 percent to $10.96 after the supplier of residential building products said it would buy privately held ProBuild Holdings for $1.63 billion in cash.
Netflix shares were up 4 percent at $472.56 after the video streaming company said Friday it was seeking to increase its share authorization by nearly 30 times as a possible first step towards a stock split.
Advancing issues outnumbered declining ones on the NYSE by 1,531 to 1,268, for a 1.21-to-1 ratio; on the Nasdaq, 1,454 issues rose and 999 fell for a 1.46-to-1 ratio.
The benchmark S&P 500 index posted 16 new 52-week highs and no new lows; the Nasdaq Composite recorded 66 new highs and 9 new lows. (Editing by Bernadette Baum)