Australian buy now-pay later outfit Afterpay has been going great guns – but it could see its shares halved in value as big names enter the business where Afterpay has been thriving, according to a US professor of marketing.

He is Scott Galloway, pictured, professor of marketing at the NYU Stern School of Business.

Among those big names now eyeing Afterpay’s business are Mastercard and Visa, Galloway has suggested in a YouTube video.

He noted that Afterpay is a pretty smart company now valued on the stock exchange at more than $9 billion. But he says the company, among others scrambling to get ahead in the buy now, pay later business, have one big problem: they lack then”defensive moats” that make them hard to displace.

“These buy now, pay later [companies] have puddles rather than moats, which credit-card companies can likely breach and step over,” he said, predicting that Afterpay and other buy now, pay later companies’ stocks will probably be halved in the next 12 months as Visa rolls out its product.