U.S. stocks posted their sixth straight day of gains on Thursday as an encouraging profit forecast from United Parcel Service lifted transportation shares, though concerns about a rise in weekly jobless claims limited the market's advance.

Financial stocks weighed on the S&P 500 as they gave back some gains after Wednesday's strong rally.

UPS late Wednesday posted a first-quarter profit that was sharply above consensus and raised its profit outlook, becoming the latest bellwether to exceed expectations.

The stock rose 5.3 percent to $68.89 while rival shipper FedEx Corp gained 1.7 percent to $95.62. The Dow Jones Transportation Average <.DJT> climbed 1.7 percent, hitting a 52-week high in intraday trading.

New U.S. jobless claims unexpectedly soared last week due to applications delayed by the Easter holiday.

We continue to see better-than-expected numbers across a variety of sectors, which shows economic improvement, but ultimately we need to see good labor market data to confirm that the recovery is in place, said Channing Smith, vice president of Capital Advisors, Tulsa, Oklahoma.

Google Inc fell 4.6 percent to $568 in extended trading after reporting its first-quarter results. The stock rose 1.1 percent in anticipation of the results to close at $595.30 and is up about 5 percent this week.

All the metrics were good, Smith said. They just weren't good enough.

Also after the market close, Advanced Micro Devices Inc reported first-quarter revenue that beat expectations, sending the stock up 0.9 percent to $10.25 after the bell.

The Dow Jones industrial average <.DJI> rose 21.46 points, or 0.19 percent, to end at 11,144.57. The Standard & Poor's 500 Index <.SPX> edged up 1.02 points, or 0.08 percent, to 1,211.67. The Nasdaq Composite Index <.IXIC> gained 10.83 points, or 0.43 percent, to close at 2,515.69.

Earlier, the S&P 500 touched an intraday high at 1,213.92, its highest in 19 months. The Dow also reached a 19-month intraday high at 11,154.55 earlier in the session.

CITI SLIDES IN HUGE VOLUME

Citigroup was the most actively traded name on the Big Board, losing 2.4 percent to $4.81. According to NYSE Euronext data, nearly 1.5 billion shares of Citigroup changed hands on the New York Stock Exchange -- or 25 percent of the day's 5.995 billion shares traded. Citigroup is set to report quarterly results on Monday.

S&P 500 companies' quarterly earnings are forecast to rise 38.2 percent from a year ago, slightly better than the 36.6 percent increase forecast on April 1, according to Thomson Reuters data.

Worries that debt-plagued Greece was ready to use an emergency bailout package weighed on sentiment earlier in the day, but the S&P 500 remained well above the key 1,200 mark and the Dow above 11,000. The recent break above those levels was the first time since September 2008.

The next key resistance level is 1,214 on the S&P 500, just shy of the 61.8 Fibonnaci retracement from the all-time high reached in October 2007 to the multi-year low reached in March 2009.

In other data released on Thursday, the Philadelphia Federal Reserve Bank's business activity index rose slightly more than expected in April, while the New York Federal Reserve's Empire State manufacturing index rose to a six-month high.

Analysts have been more optimistic about the U.S. stock market's performance for the year. On Thursday, Bank of America-Merrill Lynch raised its year-end target for the S&P 500 to 1,300 from 1,275.

About 10.16 billion shares traded on the New York Stock Exchange, the American Stock Exchange and Nasdaq, above last year's estimated daily average of 9.65 billion.

Decliners slightly outnumbered advancers on the New York Stock Exchange by a ratio of about 8 to 7, while on the Nasdaq, about five stocks rose for every four that fell.

(Reporting by Ryan Vlastelica; Additional reporting by Leah Schnurr; Editing by Jan Paschal)