SHANGHAI (Bloomberg) - Google Inc., the owner of the world's most-used Internet search engine, halved the length of time it keeps users' records to assuage privacy concerns.

Google will keep search data for nine months instead of the minimum 18-month period introduced last year, chief privacy lawyer Peter Fleischer said in a blog post. Google now holds on to search records for less time than Yahoo! Inc. and Microsoft Corp., the second and third most used search sites.

The change is a victory for US and European lawmakers who said search engines keep too much personal data with little oversight in how they use them. Google, which handles almost two- thirds of US searches, says the records have helped it create new Web services, fight online fraud and reduce unwanted e-mails.

"While we're glad that this will bring some additional improvement to privacy, we're also concerned about the potential loss of security, quality and innovation that may result from having less data," Mr. Fleischer said. "It's difficult to find the perfect equilibrium between privacy on the one hand, and other factors such as innovation and security on the other."

Google rose $5.04, or 1.2 percent, to $424.99 at 9:30 a.m. New York time in Nasdaq Stock Market trading. The shares had declined 39 percent this year before yesterday.

Last year, Sunnyvale, California-based Yahoo and Microsoft agreed to make data anonymous after 13 months and 18 months, respectively. Google handles almost twice as many US searches as its two rivals combined.

Google's latest reduction still falls short of European guidelines.

Officials from 27 European Union nations agreed in April that search engines should not keep data for more than six months without justification.

Last month, US Representative John Dingell and other lawmakers sent a letter to 33 companies, asking them to explain whether they target advertising based on consumers' web-surfing habits. Mr. Dingell, a Democrat from Michigan, leads the House Energy and Commerce Committee, which oversees Internet issues.

Google and other search sites responded by disclosing that they do not explicitly tell consumers every time they're being targeted with online ads because their practices are outlined in their privacy policies.

Google, Yahoo and Redmond, Washington-based Microsoft are all vying for a greater share of Internet advertising sales, which probably will surge to $65 billion this year, according to Framingham, Massachusetts-based researcher IDC. More than a third of that will come from searches.