Visa slips 5.5% on report the DOJ is investigating the firm's debit-card practices

• Shares of Visa fell as much as 5.5% on Friday.
• The Department of Justice is investigating Visa's debit-card practices, the Wall Street Journal reported.
• Visa reportedly limited merchant's ability to route debit-card transactions over less expensive networks.

Shares of Visa slipped as much as 5.5% on Friday after a report said the Department of Justice is investigating the firm's debit-card practices.

Visa is under investigation for "anticompetitive practices" in the debit-card market, reported the Wall Street Journal, citing unnamed sources.

The Foster City, California-based financial services corporation is specifically being investigated for possibly limiting merchants' ability to route debit-card transactions over less expensive networks.

Visa and other credit card companies use what are called "network fees" as a main source of revenue. Although these fees are invisible to consumers, they can heavily weigh on merchants and be very lucrative for card companies.

The DOJ is probing whether Visa's move to prevent merchants from avoiding their network fees could allow the firm to illegally maintain its leading market position, the WSJ reported.

Visa stock is down nearly 7.5% since hitting March 11 record highs of over $226 per share.

Before this latest news analysts were overwhelmingly bullish on shares of Visa. The company boasts 49 "buy" ratings, six "neutral" ratings, and zero "sell" ratings from analysts.

Most recently, Morgan Stanley maintained their buy rating and $253 price target on Visa in a note to clients on March 16.

Visa stock traded down 5.16% as of 1:23 p.m. ET on Friday.