Visa Europe currently has a licensing agreement with its parent company but it may now be returning to its original owner.

Visa Inc., the world’s most popular payment processor is in talks to acquire its former subsidiary Visa Europe Ltd. According to a source close to the discussions the deal could be worth up to $20 billion.

The talks are in very early stages and a price has not been agreed for either party according to a source who asked not to be identified due to the private nature of the negotiations. The price range that they would be willing to pay is around $15 billion to $20 billion, the people said.

Just before Visa’s IPO in 2008 its European division split from the company and ever since analysts have been speculating that they may merge. Visa Europe is currently owned by over 3,000 banks in Europe; a put option is in place forcing its former parent to purchase it within roughly nine months providing 80 percent or more of its board agrees, as stated in according to company filings.

Jason Kupferberg, a Jefferies Group LLC analyst, said in a note to clients in November that the downside to the former U.S. parent company taking over is that it may expose itself to European Union regulations and potential litigation involving Visa Europe if the option is exercised.

Visa has said it would like to move Visa Europe into the larger company at its earlier convenience. Analysts regularly question Visa about the possibility of the purchase, when Visa CEO Charlie Scharf was asked in April on an earnings call he said:

“Until they get 80 percent, then it’s not going to happen. So I really don’t know.”

“Over the long term, we absolutely would love Visa Europe to be part of the company,” Scharf said. “It just to us makes extraordinary amount of sense. Sooner is better.”

Visa has said they expect there to be a 40 percent chance that Visa Europe would exercise the put, and estimated last month that doing so would cost the company more than $10 billion. The final price depends on a range of variables which could move the price tag all the way up to $20 billion.

The question that Visa faces is how to finance such an acquisition, Scharf did say at an investor conference they may consider issuing debt to fund the purchase of Visa Europe.

“We think the company should have debt,” “The question is, at what time, for what reason. And, when you got someone with a put the size of Visa Europe, we need to be conscious of factoring that financing into our thinking” said Scharf.

Visa Europe currently has a licensing agreement with Visa; according to its annual report they managed over 500 million accounts and processed in excess of 16 billion transactions last year. The company earned 219.8 million euros ($246 million) in 2014 which was up 29 percent from the previous year.

Visa gained 4.3 percent on Friday to $69.47 a share by the close of trading in New York, giving it a market value of $170 billion.