* S&P 500, Nasdaq on track for six-day advance
* Netflix up after results, Facebook gains on upgrade
* Allergan soars as Ackman and Valeant bid for company
* Indexes up: Dow 0.68 pct, S&P 0.67 pct, Nasdaq 1.13 pct (Updates to mid-afternoon, changes byline)
By Chuck Mikolajczak
NEW YORK, April 22 (Reuters) - U.S. stocks rose on Tuesday, with both the S&P 500 and Nasdaq on track for a sixth straight day, buoyed by a host of solid earnings reports along with strength in the healthcare sector.
Netflix Inc surged 5.9 percent to $369.04 a day after showing strong subscriber growth, a sign the trading favorite still had room to grow despite recent concerns over its valuation. With the day's gain, the stock moved to the plus side for the year after a 21 percent drop in March.
Healthcare, up 1.5 percent, was the best performing of the 10 major S&P sectors, as Allergan Inc jumped 15.8 percent to $164.48 a day after activist investor William Ackman teamed up with Canadian drugmaker Valeant Pharmaceuticals International Inc to bid for the company. U.S.-listed Valeant shares gained 7.6 percent to $135.56.
Also providing support to the sector was a deal between Novartis and GlaxoSmithKline, in which the two companies traded over $20 billion worth of assets in an effort to cope with healthcare spending cuts and generic competition. U.S.-listed shares of Novartis gained 1.4 percent to $86.67 while shares of Glaxo trading in New York advanced 4.1 percent to $55.31.
Facebook Inc shares rose 3 percent to $63.08 to help boost the Nasdaq 100 and S&P 500. Credit Suisse upgraded the social networking company to "outperform" on higher expectations for the company's long-term average revenue per user.
Better-than-expected earnings have lifted equities recently, though companies have largely been exceeding reduced forecasts. Profits are seen rising 1.1 percent this quarter, down from the 6.5 percent growth rate estimated at the start of the year.
"Earnings are certainly providing a constructive context for engagement," said Peter Kenny, CEO of Clearpool Group in New York. "They are also importantly providing forward looking-guidance and confidence the rally we've had over the previous three or four years, though we've seen a pause in the first quarter, is not a compelling reason to sell equities."
Dow components Travelers Cos Inc and United Technologies Corp both beat expectations, and United Tech raised the low end of its full-year profit outlook. Shares of Travelers rose 0.6 percent to $86.89 while United Tech was up 1.3 percent at $119.89.
McDonald's Corp reported earnings that fell alongside a drop in U.S. same-store sales, and its shares slipped 0.3 percent to $99.42.
With 20 percent of the S&P having reported, 63 percent have topped earnings expectations, according to Thomson Reuters data, even with the long-term average. On the revenue side, 51 percent have exceeded forecasts, below the 61 percent long-term average.
The Dow Jones industrial average rose 112.02 points or 0.68 percent, to 16,561.27, the S&P 500 gained 12.63 points or 0.67 percent, to 1,884.52 and the Nasdaq Composite added 46.47 points or 1.13 percent, to 4,168.016.
Both the S&P and Nasdaq are on track for a sixth straight day of gains. The S&P has gained 3.8 percent over that period while the Nasdaq is up 4.2 percent. (Reporting by Chuck Mikolajczak; Editing by Nick Zieminski)