NEW YORK ( TheStreet) -- It's time to load up on shares of Visa ( V), according to KBW analyst Sanjay Sakhrani. Visa's shares closed at $178.35 Wednesday, down 7% since July 30, which was the day before U.S. district court judge Richard J. Leon in Washington ruled that the Federal Reserve had "clearly disregarded Congress's statutory intent by inappropriately inflating all debit card transaction fees by billions of dollars and failing to provide merchants with multiple unaffiliated networks for each debit transaction." Meanwhile, shares of MasterCard ( MA) rose 5% since July 30, to close at $629.98 Wednesday. Judge Leon ruled against the Federal Reserve's final rules on the Durbin Amendment of the Dodd-Frank Wall Street Reform and Consumer Protection Act, which were implemented by the regulatory during the fourth quarter of 2011. The Durbin Amendment requires caps on interchange fees charged by banks to process debit card transactions for merchants, and also requires "non-exclusivity" for the network processing the transaction. The Federal Reserve's interpretation of the Durbin Amendment calls for merchants to have a choice on which network to use to process a debit card purchase, but only if the customer is required to use a PIN number at the point of sale. In his ruling, Judge Leon wrote "First, the interchange transaction fee and network non-exclusivity regulations are fundamentally deficient. It appears that the Board completely misunderstood the Durbin Amendment's statutory directive and interpreted the law in ways that were clearly foreclosed by Congress." The Judge's interpretation of Durbin is that merchants should be able to choose the processing network for each debit card purchase, whether or not the customer uses a PIN. If Judge Leon's opinion on non-exclusivity for transaction networks sticks, it can only mean good news for MasterCard and bad news for Visa. "Visa has more to lose than gain since it has 71% share in signature debit versus MasterCard at 29% in the U.S," according to JPMorgan analyst Tien-tsin Huang. "Assuming competition results in shift to 50/50 share and pricing stays rational, we conservatively see $540M of revenue that could shift from Visa (6% revenue hit or ~$0.51 in EPS) to MasterCard (9% revenue benefit or ~$2.74 in EPS)," Huang wrote in a July 31 note to clients.