Bitcoin has been on a tear, and major merchants are starting to take notice—seriously.

Many of the important global retailers, including Starbucks, Subway, Dell, Expedia, Overstock.com and Microsoft, are already on board the cryptocurrency train. But what about the other merchants?

Several months ago, the team behind CoinGeek started an experiment in which they sent $100 of bitcoin via a QR code to the financial directors of 20 top retail brands—most of them operating online—that have yet to accept the digital currency.

Among those selected for the experiment were Alibaba, Amazon, Tesco, Staples, Uber, MacDonalds, Netflix, Airbnb, American Airlines, LVMH, AT&T, CVS Health, Tesla, Apple, FedEx, John Lewis PLC, Spotify, BMW and Red Bull.