Earlier this month, Google announced that it was giving mobile users the ability to order food directly from its search results, signaling the possibility that the next phase of search’s evolution will be transactionalization.

As I wrote at the time, “it’s not hard to imagine Google applying transactional functionality to other types of search,” and product search seemed like one of the most obvious search categories ripe for transactional features.

Not more than two weeks later come reports that Google is about to add buttons to search engine results that enable users to easily initiate a purchase.

As detailed by The Wall Street Journal:

The search giant will start showing the buttons when people search for products on mobile devices, according to people familiar with the launch.

The buttons will accompany sponsored—or paid—search results, often displayed under a “Shop on Google” heading at the top of the page. Buttons won’t appear with the nonsponsored results that are driven by Google’s basic search algorithm.

If shoppers click on the buy buttons, they will be taken to another Google product page to complete the purchase, the people explained. On that page, they will be able to pick sizes and colors and shipping options, as well as complete the purchase, one of the people said.

According to the Journal’s Alistair Barr and Rolfe Winkler, Google will be facilitating the transactions but the orders will be fulfilled by retailers. Macy’s is one of the retailers reported to be in talks with Google.

As with its food delivery feature, Google will only display buy buttons for mobile searchers and is initially going to display the buttons to a small percentage of users.

A double-edged sword for retailers?

Needless to say, Google’s push to transactionalize search could be a boon for Google as it seeks to defend search ads against other channels, like paid social ads.

If successful, Google’s transactionalization efforts could even allow it to take a piece of sales, although The Wall Street Journal says that isn’t on the table initially.

But despite its potential to drive sales, buy buttons won’t necessarily be an easy sell to retailers. As Barr and Winkler detail, “Some retailers said they worry the move will turn Google from a valuable source of traffic into a marketplace where purchases happen on Google’s own websites. The retailers, who wouldn’t voice their concerns publicly, fear such a move will turn them into back-end order takers, weakening their relationships with shoppers.”

To allay fears, Google will reportedly co-brand its order pages and give retailers the ability to ask customers to opt in to their mailing lists. But according to one source, credit card information won’t be shared and obviously, retailers will necessarily lose control over the overall shopping experience. That, for instance, will limit their ability to upsell customers and maximize metrics like average order value.

Ultimately, the big question is whether Google’s buy buttons deliver incremental sales or cannibalize sales from existing customers. For Google to transactionalize product search with the help of retail partners, it will have to quickly prove it can do the former.