US STOCKS-Wall St higher as earnings cheer investors

* Morgan Stanley (Xetra: 885836 - news) rises after results beat expectations

* Vivint Solar (NYSE: VSLR - news) soars after SunEdison (NYSE: SUNE - news) deal

* IBM (NYSE: IBM - news) to report after the bell

* Greece banks reopen after three weeks

* Indexes up: Dow 0.07pct, S&P 0.01 pct, Nasdaq 0.08 pct (Updates to open)

By Tanya Agrawal

July 20 (Reuters) - Wall Street opened slightly higher on Monday, with the Nasdaq composite hitting a record for the third straight day, as better-than-expected earnings from big companies boosted investor confidence.

On Friday, strong earnings from Google (Xetra: A0B7FY - news) pushed the tech-heavy Nasdaq to a record close, which gained 4.3 percent for the week, its largest weekly gain since October while the S&P 500 stopped just short of its record high.

Tech earnings will continue to be in focus this week with IBM reporting after the close on Monday and other big tech giants such as Apple (NasdaqGS: AAPL - news) , Yahoo (NasdaqGS: YHOO - news) and Microsoft (NasdaqGS: MSFT - news) expected to report later this week.

"If things stay quiet on the Greece and China front, it will be good for the market to focus on earnings, which should be driving the market in the first place," said Randy Frederick, managing director of trading and derivatives for Charles Schwab in Austin, Texas.

Of the companies that have reported earnings so far, 71 percent have reported earnings above analyst expectations, above the 63 percent that typically beat in a quarter.

However, only 51 percent have beaten on revenue, below the 61 percent.

U.S. companies were expected to post their worst sales decline in nearly six years in the second quarter, in part due to the strong dollar that reduces the value of U.S. companies' overseas income. Profit is expected to have fallen 2.9 percent, according to Thomson Reuters (Dusseldorf: TOC.DU - news) estimates.

The dollar index was up marginally at $97.91. It had earlier hit a three-month high due to expectations of a Federal Reserve rate hike this year.

Investor (Stockholm: INVE-A.ST - news) sentiment was also buoyed by positive signals from Greece. Greek banks reopened their branches across the country after a three-week shutdown.

At 9:39 a.m. ET (1339 GMT) the Dow Jones industrial average was up 13.43 points, or 0.07 percent, at 18,099.88, the S&P 500 was up 0.13 points, or 0.01 percent, at 2,126.77 and the Nasdaq Composite was up 4.26 points, or 0.08 percent, at 5,214.41.

Five of the 10 major S&P 500 sectors were lower with the energy index leading the decliners with a 0.64 percent fall.

Morgan Stanley shares were up 1.2 percent to $46.48 after the U.S. bank's consolidates net revenue rose 13 percent.

PayPal Holdings (NasdaqGS: PYPLV - news) was up 4.4 percent to $40.22, on its trading debut after it split from e-commerce company eBay .

Vivint Solar soared 44.2 percent to $15.68 after solar company SunEdison said it would buy the company in a deal valued at about $2.2 billion, including debt. SunEdison was up 3.3 percent to $32.59.

Horizon Pharma (NasdaqGS: HZNP - news) jumped as much as 6.5 percent to a record of $39.79, after the Irish drugmaker raised its full-year sales forecast.

Declining issues outnumbered advancers on the NYSE by 1,669 to 985. On the Nasdaq, 1,301 issues fell and 985 advanced.

The S&P 500 index showed 23 new 52-week highs and 22 new lows, while the Nasdaq recorded 66 new highs and 40 new lows. (Editing by Don Sebastian)