Arthas' technology will play a large role in the Web portal's person-to-person payment service, Yahoo PayDirect, which is expected to launch later this year.
San Francisco-based Arthas lets individuals electronically send money to and receive money from anyone with an email address. People can also send personalized electronic bills that can be paid online using the payment service.
The acquisition is Yahoo's latest play to add e-commerce to its traditional Internet searching and directory services. The company could integrate the payment service with its online auction or classified ad Web sites, according to a release.
On Monday, Yahoo announced that it has created a business-to-business directory that offers listings of e-commerce sites for industrial and commercial supplies, such as drills and steel.
Several consumer sites are looking to expand and increase revenues by incorporating business-to-business services online. Last week, leading auction site eBay announced plans to launch a business exchange targeting the small-business market.