Grocery retailers are set to “close the gap” with Amazon as they develop new revenue streams that could be worth billions, according to Goldman Sachs.

While brick-and-mortar stores’ push into e-commerce is costly, there is a “compensating upside” that investors have overlooked, the bank said: their ability to make money from selling ad space on their websites.

It names six grocery stocks that were particularly well placed to benefit from this.

Selling media space to consumer-packaged goods companies could see grocers make $15 billion-$20 billion in the U.S. alone by 2025, Goldman’s analysts, led by Jason English, wrote in a note published Wednesday. They said this could be “substantially larger” if expanded to other manufacturers like clothing and sporting goods.

Here’s the list of the bank’s “largest gainers” — the large brick-and-mortar grocers it says are “uniquely advantaged” to tap into this new revenue stream: