When Snap blew its first quarter as a public company last May and its stock cratered, my reaction was that it was “by no means game over” for the young company. Snap was arrogant, untested, and faddish. And its founders controlled the company. None of this was news. Its anemic user growth was, however, and investors punished the stock, sending it to its IPO levels of about $17 a share.

Wednesday Snap’s shares jumped nearly 50% because suddenly things are moving in the right direction. It is adding users. Revenues are growing impressively. It is tending to Android users, a category that was weirdly lagging a year ago. And Snap’s traction may be the first tangible sign outside of Facebook’s own results that advertiser disgust with the “meaningful social interaction” company is having a meaningful impact.

The good and the bad for Snap (SNAP) is that it’s still tiny, accounting for perhaps 1% of a market dominated by Facebook (FB) and Google. That means opportunity but also an uphill climb.

The lesson to remember here is that investors are fickle and unemotional. They’ll whine about anything and everything, like “unfair” dual-class ownership structures. And the minute the narrative improves, their ire turns to love.

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Briefly … I love how Daisuke Wakabayashi of The New York Times is providing a running commentary on the way Travis Kalanick speaks in his testimony at the Waymo-Uber trial in San Francisco. Tuesday he focused on Kalanick’s use of the expression “jam sesh,” for jam session, or a time for entrepreneurs (not musicians) to sit around brainstorming on business ideas (not playing music). Wednesday Wakabayashi quoted Kalanick saying Google (GOOGL) became “unpumped” with Uber as it invested in self-driving cars. Only Kalanick speaks this way, and kudos to Wakabayashi for recording it. … Recommended reading: The New Yorker details the dangerously unprepared way the son-in-law of the President of the United States has been conducting foreign policy. Of note, the print version of the article said Jack Ma had invested in Cadre, a company Jared Kushner co-founded. An online correction said David Yu, co-founder of a private-equity firm with Ma, invested in the company. The firm in question in Yufeng Capital, based in Shanghai, and unless Yu invested in Cadre personally the distinction is a curious one, as is the correction.