US STOCKS-Wall St rebounds as investors buy beaten-down shares

* Gilead leads as biotechs end 5-day losing streak

* Railcar makers gain on new tough oil-train safety rules

* Social media stocks fall with LinkedIn

* Consumer sentiment, auto sales rise

* Indexes up: Dow 0.95 pct, S&P 0.98 pct, Nasdaq 1.15 pct (Updates to late afternoon)

By Caroline Valetkevitch

May 1 (Reuters) - U.S. stocks bounced back sharply on Friday as investors snapped up some of this week's most beaten-down shares, including in the healthcare and technology sectors, and as data pointed to a pickup in economic activity.

Apple (NasdaqGS: AAPL - news) gave the three major indexes their biggest boost, with a 2.3 percent increase to $128.01, reversing Thursday's decline. The S&P tech sector was up 1.2 percent, while the Nasdaq was on track to snap a four-day losing streak.

Biotech shares also rebounded and were set to snap a five-day losing streak. The Nasdaq Biotech Index was up 2.7 percent.

Shares (Berlin: DI6.BE - news) of Gilead rose 5.2 percent to $105.78 after its quarterly profit nearly doubled. The S&P healthcare index was up 1.3 percent and among the day's best-performing sectors.

"Today's the first day of a new month, and we're seeing a lot of institutional buying coming in," said Adam Sarhan, chief executive of Sarhan Capital in New York. "The buy-the-dippers have come in" to bid up stocks, which is a sign of a healthy market.

Indexes were still on track to post losses for the week, however. Social media shares were among the weakest performers following disappointing outlooks and results this week from several key players including Twitter (Xetra: A1W6XZ - news) .

LinkedIn dropped 19 percent to $204.07, a day after reporting results.

Investors were also buoyed by an encouraging batch of data for April that suggested the economy was pulling out of a first-quarter soft patch.

At 3:20 p.m. the Dow Jones industrial average rose 169.69 points, or 0.95 percent, to 18,010.21, the S&P 500 gained 20.5 points, or 0.98 percent, to 2,106.01 and the Nasdaq Composite added 56.78 points, or 1.15 percent, to 4,998.20.

Consumer sentiment jumped and vehicle sales were stronger-than-expected in April, while manufacturing expansion in the month held steady at near a two-year low.

Railcar makers gained after tougher oil-train safety standards, including rules to phase out older tank cars in three years, were announced.

Greenbrier gained 5.6 percent to $60.97, while Trinity Industries (NYSE: TRN - news) rose 6.3 percent to $28.82. American Railcar was up 5.3 percent at $55.90.

Advancing issues outnumbered declining ones on the NYSE by 1,826 to 1,197, for a 1.53-to-1 ratio on the upside; on the Nasdaq, 1,589 issues rose and 1,175 fell for a 1.35-to-1 ratio favoring advancers.

The benchmark S&P 500 index was posting 10 new 52-week highs and no new lows; the Nasdaq Composite was recording 33 new highs and 64 new lows. (Additional reporting by Tanya Agrwal; Editing by Savio D'Souza and Meredith Mazzilli)