Shares of MasterCard and Visa are rallying after the Chinese government indicated that it will open up the bank-card clearing market in June.

Right now, China UnionPay has a virtual monopoly in the country's bank card market, with Visa and MasterCard relying on their network and paying a fee to process transactions in China.

But this development could open up the market to both companies directly, according to Reuters.

Starting on June 1, foreign companies will be able to apply for licenses for bank card clearing businesses in China. Reuters' report cited comments from China's central bank, which said, "Opening up the market for bank card clearing will help improve the country's card-clearing services through market competition."

Bank card transactions totaled $6.84 trillion last year, up 33% from the previous year, according to Reuters, citing data from China’s central bank.

In morning trading on Tuesday, MasterCard rallied by nearly 5% to as high as $92 per share, the highest its been since early March. Visa jumped by more than 6.5% to as high as $69.57, also the highest in over a month.

Here's a chart showing the pop in Visa's share price, which is now at an all-time high:

And in MasterCard's:

(via StreetInsider)