Why is Visa up for Sale?

On 25th. of February, the BBC reported that Visa, the world's biggest credit card network was planning to raise a record amount of money by issuing shares and listing on the New York Stock Exchange.

'Visa hopes to raise more than $18bn (£9bn) from the listing, which would make it the largest Initial Public Offering (IPO) in the US to date. '

From this amount, $10.2 billion would be paid to the banks who own the network, and $3 billion would be set aside to cover the cost of current ongoing litigation. Charges include allegations of price fixing by major retailers, and anti competitive activities towards other card operators.

There is one question that begs the asking however. If you are the world's largest credit card company, and you have made huge profits over so many years, why would you want to sell of part of the business.

Do they think that consumers will spend less on their credit cards; that bad debts might increase, or are the banks that own Visa so strapped for cash that they have to start carving up the golden egg laying goose?