As people shop more on their phones, fraudsters too are moving to mobile.

According to a new study, businesses on average lose $92.3 million annually in revenue to mobile fraud.

That equates to as much as 25 percent of mobile sales for some businesses, says the study commissioned by RSA and Telesign. The study polled 250 businesses with an average revenue of $2.54 billion.

Half of participants said mobile sales represent 50 to 75 percent of their revenue. Most businesses also said they expect their percentage of mobile revenue to double in the next five years.

This means unmitigated fraud could force these companies to lose out on a lot of revenue. Only 8 percent of companies in the study experience no mobile fraud at all.

The majority of fraud appeared attributable to a lack of mobile security. One in four businesses don’t require mobile users to login before making a purchase. Going forward, enterprises need to start investing in mobile authentication.

Organizations like FIDO are trying to get the word out to businesses that there are ways to better secure their mobile shopping experiences through biometrics, tokens, and two-factor authentication. Late last year, FIDO outlined a standard for implementing identity authentication that could go a long way towards helping businesses prevent mobile fraud in the future.