Cathie Wood, chief of Ark Investment Management, frequently adjusts her top positions, adding to a holding when the stock falls and selling when it rises. Last week she did some notable buying. This week she was selling,

Wood (Mama Cathie to her followers) rocketed to fame after a stupendous return of 153% in 2020 and easy-to-understand explanations of her investment strategy in numerous media appearances.

At this price, Shopify stock could be a buy for risk-tolerant investors like Cathie Wood. It's a bull-market buy, and as interest rates begin to come down, Shopify stock could rise regardless of its high valuation. But if you don't have the stomach for volatility, it's probably not the best candidate for your portfolio.

If you follow Cathie Wood at all, you know the chief of Ark Investment Management loves to double down on her stock positions when they decline. And that’s exactly what she did this week. Investors and analysts are split in their opinions of Wood,

Nvidia has been the king of the first wave of artificial intelligence (AI) investing. Its graphics processing units (GPUs) are being purchased by the truckload by the biggest cloud computing and AI modeling companies.

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