* S&P 500, Nasdaq on track for six-day advance
* Netflix up after results, Facebook gains on update
* Allergan soars as Ackman and Valeant bid for company
* Indexes up: Dow 0.6 pct, S&P 0.5 pct, Nasdaq 0.9 pct (Updates to midday trading)
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 of gains as a number of bellwether companies reported strong results.
Netflix Inc surged 6 percent to $369.33 a day after results showed 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 returned to slightly positive territory for the year after a 21-percent decline in March.
Also helping lift the Internet space was Facebook Inc , which rose 2.5 percent to $62.80 after Credit Suisse upgraded the social networking company to "outperform" on higher expectations for the company's long-term average revenue per user.
Dow components Travelers Cos Inc and United Technologies Corp both reported first-quarter earnings that beat expectations, and United Tech raised the low end of its full-year profit outlook. Shares of Travelers rose 0.2 percent to $86.58 while United Tech was up 1.2 percent at $119.69.
McDonald's Corp reported earnings that fell alongside a drop in U.S. same-store sales, but shares of the Dow component rose 0.2 percent to $99.88.
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.
"The season has been better than many have feared, which is helping investors feel comfortable with the pace of economic growth, not just in the first quarter but going forward," said Joseph Tanious, global market strategist at J.P. Morgan Asset Management in New York.
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 revenue, 51 percent have exceeded forecasts, below the 61 percent long-term average.
The Dow Jones industrial average was up 92.93 points, or 0.56 percent, at 16,542.18. The Standard & Poor's 500 Index was up 9.50 points, or 0.51 percent, at 1,881.39. The Nasdaq Composite Index was up 38.44 points, or 0.93 percent, at 4,159.99.
Both the S&P and Nasdaq are on track for a sixth straight day of gains. The S&P has gained 3.6 percent over that period while the Nasdaq is up 4 percent.
In company news, Allergan Inc jumped 15 percent to $163.58 a day after activist investor William Ackman teamed up with Canadian drugmaker Valeant Pharmaceuticals International Inc to bid for the company.
In the latest economic data, existing home sales fell to their lowest level in more than 1-1/2 years in March, though the decline was narrower than expected. (Editing by Nick Zieminski)