Shopify (SHOP 19.07%) stock soared 22% through 9:45 a.m. Wednesday after reporting stronger-than-expected Q2 sales this morning.

Instead of the $2.55 billion Wall Street was expecting, Shopify collected $2.68 billion in revenue in Q2, helped by strong "gross merchandise volume" (GMV) facilitated by its software -- $87.84 billion.

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Shopify Q2 earnings

Shopify's a bit eccentric in how it reports earnings, deemphasizing net income (and earnings per share) and focusing more on GMV, revenue, and free cash flow. In today's report, the company boasted of growing revenue 31% year over year, and earning 16% free cash flow margins on its revenue.

GMV grew 31% year over year, resulting in similar revenue growth. Free cash flow generated from these sales, however, grew slower at 27%, and operating profits were up only 21% year over year -- numbers that may discourage growth stock investors a bit once they notice them.

Is Shopify stock a buy?

Guidance may also come as something of a shock, with management forecasting sales growth to slow into the "mid-to-high twenties percentage rate" in Q3, and gross profit rising even less, in the "low-twenties." On the plus side, management forecasts free cash flow margin to be somewhere in the "mid-to-high teens."

If that's how things play out, it implies Shopify should at least maintain the 16% FCF margin it did in Q2, in the coming quarter -- and might even exceed it. That would presumably provide a bigger boost to both FCF and profits.

Speaking of which, Shopify's $200 billion market cap today prices the stock at 111 times free cash flow, and more than 87 times net profit. That's quite a high price for a stock growing at 31% -- much less the "mid-to-high teens."

Therefore, despite the earnings beat, Shopify's still a sell for me.