Facebook of Menlo Park, Calif. has acquired mobile loyalty rewards company TagTile, according to a statement on TagTile's website.

The San Francisco start up offers merchants a cube-shaped device that consumers can tap their smart phones against in order to earn offers. The price of the acquisition was not released.

"We are happy to announce that we are joining Facebook, and that they are acquiring substantially all of our assets," says TagTile in the release. "It's a huge opportunity for us to take our goal — helping businesses grow — and do it on a much, much bigger scale than we could have on our own."

The deal is the second of its kind this week for the social network. Facebook purchased photo sharing company Instagram Monday for $1 billion in cash and stock.

On Friday, TagTile said that it will not be taking on any new customers as a result of the deal, but that the service will continue to work as is for now.

Facebook has been aggressively expanding its payments business. In its S-1 filing, the social network revealed it got 15% of its $3.7 billion in revenue last year from payments. Facebook has been acquiring money transmitter licenses that enable Facebook to handle transactions and potentially transform its digital currency, Facebook Credits, into something that would allow it to compete more directly with banks.

"I think Facebook is sitting on a huge potential with their base," says Brian Riley, a senior research director in the bank cards and retail bank practice at CEB Towergroup. "It's a natural vehicle to move money around."