Square is said to be seeking to raise $250 million at a $3 billion to $4 billion valuation →

The title says it all.

Interesting bit about Square’s business though:

Still, the business doesn’t make a lot of money on a per-transaction basis. It scrapes a small fee from every transaction made on Square, which it shares with credit card companies. To become enormously profitable, it will need to increase its merchant base drastically to generate enough transactions. It’s a particularly challenging feat, given the hyper-competitive nature of the mobile payments market.