* 500.com shares rise as much as 70 pct
* Sungy Mobile shares up 44 pct
* Big banks underwriting IPOs add to investor confidence - analysts (Adds details on IPO market, fund manager comments)
By Avik Das and Aman Shah
Nov 22 (Reuters) - Shares of 500.com Ltd and Sungy Mobile Ltd, surged in their U.S. debuts on Friday, as investors bet on Chinese technology companies backed by marquee underwriters.
Investor appetite for Chinese companies seems to have recovered after a series of accounting scandals in the past couple of years dried up U.S. listings of China-based companies in 2011 from a high of 40 in 2010.
"If they (Chinese IPOs) are brought by top-tier underwriters, then investors are a lot more interested," said Francis Gaskins, a partner at IPO research company IPODesktop.com.
Deutsche Bank led the offering of online sports-lottery operator 500.com, while Credit Suisse and JP Morgan were the lead underwriters for the IPO of mobile applications maker Sungy Mobile.
Seven Chinese companies have listed in the United States this year so far compared with just two in 2012.
For a Breakingviews column on Chinese IPOs in the United States, click
In the past couple of years, companies such as timber producer Sino-Forest Corp and outdoor advertiser China Media Express were forced to delist due to accounting and corporate governance scandals.
Recently, Muddy Waters Research labeled Chinese mobile software company NQ Mobile Inc a "massive fraud".
500.com shares rose as much as 70 percent to $22 on Friday on the New York Stock Exchange, valuing the company at more than $700 million.
Shares of Sungy Mobile gained as much as 44 percent to $16.14, giving the company a market value of over $520 million.
BOOMING IPO MARKET
The rousing debuts of 500.com and Sungy Mobile underscore the resurgence in the U.S. IPO market this year - the strongest since 2007.
The total IPO issuance so far this year has already exceeded the 2012 total as equity markets soar, helped by continued economic growth and the Federal Reserve's efforts to keep interest rates low.
IPO issuance this year through October totaled $62.1 billion versus $91.1 billion in 2007, according to the Securities Industry and Financial Markets Association, a trade group that represents the largest U.S. retail brokerages.
But some fund managers are sounding a cautious note.
"We're back to a glass half-full environment as opposed to a glass half-empty environment," Jim Chanos, president and founder of Kynikos Associates, said at the Reuters Global Investment Outlook Summit on Tuesday. "If you're the typical investor, it's probably time to be a little bit more cautious."
Analysts have said that some of the biggest names coming to market this year, such as the social media star Twitter , look overvalued.
But investors are in no mood to relent. About eight companies have doubled in value on their first day of trading this year, with many more enjoying sizeable "first-day pops".
Most Chinese IPOs this year have been those of technology-focused companies, an indication that they are benefiting from U.S. investors' interest in the technology sector.
Friday's debuts come on the heels of successful listings of online travel agent Qunar Cayman Islands Ltd and 58.com Inc, a listing site billed as China's Craigslist, among others.
Shenzhen-based 500.com, a top lottery operator in China, raised about $75 million through its IPO, priced at the top end of its $11-$13 range that was raised from $9-$11 earlier.
The company is one of the two firms authorized by China's government to provide online sports-lottery sales services in the country.
China's lottery market has grown rapidly over the years due to economic growth and improving perception of the business.
500.com posted net profit of $3.36 million for the nine months ended Sept. 30, up nearly two-fold from a year earlier.
The company's user accounts more than doubled to 18.4 million as of Sept. 30 from the end of 2010, according to the IPO filing.
Total lottery sales are expected to rise about 18 percent to 308.0 billion yuan ($50.54 billion) in 2013, the company said in its prospectus, citing data from market research firm iResearch.
Founder and Chief Executive Man San Law holds a 20 percent stake in the company and venture capital firm Sequoia Capital China has a 14 percent stake.
Sungy Mobile priced its 7 million American depositary shares at $11.22 each, within its $9.50-$11.50 range.
The company reported a profit of nearly $10 million on revenue of $37.58 million for the nine months ended Sept. 30. ($1 = 6.09 Chinese yuan) (Additional reporting by Maria Ajit Thomas; Editing by Kirti Pandey and Saumyadeb Chakrabarty)