(Adds details, analyst comment)
June 10 (Reuters) - Synchronoss Technologies Inc (SNCR.O) said on Tuesday that its account activation technology will not be used with Apple Inc's (AAPL.O) new 3G iPhone, sending the communication software maker's shares down about 19 percent to a 52-week low.
Synchronoss, which gets paid when U.S. iPhone customers activate their devices with AT&T Inc (T.N), said the loss of that business was already factored into the forecast it gave last month and that had prompted several brokerages to downgrade its stock.
Synchronoss will not participate in the on-site, retail store activations associated with the 3G iPhone, the company said in a filing with the U.S. Securities and Exchange Commission.
Apple on Monday announced the 3G version of iPhone, which is expected to go on sale July 11.
The company had derived 72 percent of its first-quarter revenue from business related to AT&T.
Deutsche Bank analyst Tom Ernst cut the price target on Synchronoss stock to $24 from $30 to reflect the removal of the large iPhone upside potential. Ernst kept his "buy" rating on the stock.
In the filing, Synchronoss said it will continue its relationship with AT&T as it relates to the activation and provisioning of Apple iPhones.
The company's shares, which has lost about 62 percent of their value this year, were down more than 13 percent at $11.50 in afternoon trade.
The stock touched a low of $10.85 earlier in the day and was among the top percentage losers on Nasdaq. (Reporting by Scott Hillis in San Francisco and Bijoy Koyitty in Bangalore; Editing by Richard Chang and Deepak Kannan)