The Consumer Financial Protection Bureau has targeted a number of buy now, pay later companies, with shares plummeting as the news spreads.

The US regulator has focused on five companies: Affirm, Afterpay, Klarna, PayPal, and Zip.

“The CFPB is concerned about accumulating debt, regulatory arbitrage, and data harvesting in a consumer credit market already quickly changing with technology,” the regulator said in its statement.

Afterpay is in the process of selling to Square, whose shares dropped 4.6 per cent in light of the news, a year-long low for the Jack Dorsey-ran company.