Citigroup Inc. has formed a venture with Microsoft Corp. to compete with Mint Software Inc., the personal-finance Web site that Intuit Inc. has agreed to buy for $170 million.

Citigroup and Microsoft have spent about $5 million on the project since it was started this year, according to people familiar with the matter.

The venture, tentatively named Bundle, is led by Jaidev Shergill, an executive vice president in Citigroup's growth ventures and innovation unit, its in-house incubator of start-up businesses. Like Mint, the venture would let users monitor accounts at multiple banks and brokerages.

The Citi-Microsoft venture aims to develop its own site in the next one to two years, one of the people said.

Both companies want to assure themselves that Intuit does not get too far ahead in a business they believe has growth prospects, the people said.

The venture has recruited Dan Ariely, a behavioral economics professor at Duke University in Durham, N.C., as an adviser, Ariely said in an interview.

"I'm doing research about how people think about money, and what kind of mistakes people make when they think about money," he said in an interview last week. "The question is, can we use software to help people reason better about what they're doing, give them better information and make sure that the decisions they're making are the right ones?"

Microsoft runs MSN Money, a Web site that displays stock quotes; offers tools for tracking bank accounts and publishes articles and columns on investments, personal budgeting and credit repair. Citigroup's U.S. consumer Web site lets customers see accounts, make payments, transfer money and set up alerts to warn when balances fall too low.

Mint, a Mountain View, Calif., company, offers a free Web site that consumers use to track their spending and account balances. It makes money by charging financial companies referral fees for steering customers their way. Founded in 2006, Mint said last month that it had received more than $31 million of venture funding.

This year Citi folded its year-old "myFi" personal-finance Web site into the company's U.S. consumer banking operation. MyFi offered features similar to those of Mint, such as aggregating account balances from multiple banks and brokerage firms while also allowing customers to transact banking business.

Citigroup said this month that Microsoft had helped it design its Citibank Direct BE, an online-banking program meant for corporate treasurers and financial officers.

Thomas Noyes, the managing partner of Starpoint LLP, a Charlotte bank consulting company, said Citi Chief Executive Vikram Pandit wants to restore his company's reputation as an innovator but, after last year's $45 billion government bailout, he may have to justify the cost of each project.

"A key question to be asked on any investment is what value this is bringing to Citi's current customers or its current lines of business," said Noyes, who until 2007 headed Citigroup's international Internet and mobile banking businesses.

Citi spokesman Steve Silverman declined to comment, as did Microsoft spokeswoman Lisa Gurry.