(Tech stock columnist Jon D. Markman publishes Strategic Advantage, a lively, lucrative guide to investing in the digital transformation of business and society. Click here for a free trial.)

Grassroots eCommerce is the next big digital investment opportunity. There is a clear leader in the space. Investors should get on board now.

Execs at YouTube announced Wednesday that tests have begun for shopping directly from livestream media. Managers are embedding an eCommerce platform for YouTube content creators and influencers.

Investors should buy Shopify ( (SHOP) - Get Shopify, Inc. Class A Report). Let me explain.

Something important is happening in retail. Sales managers at Amazon.com ( (AMZN) - Get Amazon.com, Inc. Report) realized long ago that they could scale online shopping faster and more efficiently by shifting the burden of inventory to third-party sellers.

Amazon Marketplace is a fee-based platform operated by Amazon.com. It provides warehouse and logistics operations to independent sellers on the site. The customer-facing part of the business looks like Amazon.com. Behind the scenes, third-party sellers are taking most of the risks.

It’s a great business and Walmart ( (WMT) - Get Walmart Inc. Report), Facebook ( (FB) - Get Facebook, Inc. Class A Report), TikTok, and Alphabet ( (GOOGL) - Get Alphabet Inc. Class A Report), the parent company of YouTube want in.

The problem is these large companies have no experience building consumer-friendly eCommerce software. Moreover, there is no reason for them to be in that business. So they are outsourcing.

Enter Shopify.

The Ottawa, Canada-based company cut its teeth building eCommerce shops for most of the third-party sellers on Amazon Marketplace. Managers also secured deals to do the same for Walmart, Facebook, TikTok, and Alphabet.

Shopify is building what looks like a monopoly on the future of third-party sellers and so-called influencer merchandising. YouTube is a natural fit.

Jim Cramer of theStreet.com says Shopify puts small businesses on par with the big guys.

It’s better than that: Shopify wins on both ends. Its software is the preferred gateway to the biggest social media platforms for millions of Mom and Pop shops.