Billionaire Stanley Druckenmiller Kicked Micron to the Curb in the Second Quarter in Favor of an AI Superstar That's Gained 13,700% Since Its IPO

Arguably, few events are more exciting for investors than the filing of Form 13Fs with regulators. No later than 45 calendar days after a quarter ends, institutional investors with at least $100 million in assets under management are required to file a 13F detailing their second-quarter buying and selling activity.

Among billionaire money managers, few 13Fs are more anticipated than Stanley Druckenmiller's. Duquesne Family Office's billionaire boss has a knack for spotting amazing deals hiding in plain sight and has an exemplary track record of selling at the right time. During the second quarter, Druckenmiller kicked red-hot artificial intelligence (AI) stock Micron Technology (NASDAQ: MU) to the curb and piled into AI superstar Alphabet (NASDAQ: GOOGL)(NASDAQ: GOOG), which has rallied 13,700% since its initial public offering (IPO) in August 2004.

Duquesne Family Office's Stanley Druckenmiller is one of Wall Street's most followed billionaire money managers. Image source: Getty Images.

Billionaire Stanley Druckenmiller gave Micron the boot

Duquesne's billionaire investor was a busy bee in the second quarter, exiting nearly two dozen holdings and reducing 11 others. Perhaps no sale stands out more than the 23,400 shares sold of memory and storage solutions behemoth, Micron.

Profit-taking likely explains Druckenmiller's exit. The average security in Duquesne's investment portfolio is held for just seven months, indicating that its chief investor isn't afraid to ring the register when opportunities present themselves. Between March 31 and the end of June, Micron shares nearly quadrupled in value.

But profit-taking might not be the full story.

Historically, memory and storage solutions providers are highly cyclical. In hindsight, buying stocks like Micron when their financial outlook is poor has proven fruitful for patient investors. Conversely, selling memory and storage stocks when they have historically low forward price-to-earnings ratios and possess exceptional pricing power has been the smart move.

Micron will likely need everything to go right with the AI infrastructure build-out to sustain its trillion-dollar market cap.

Image source: Getty Images.

Duquesne Family Office's boss piles into Alphabet

At the other end of the spectrum, Druckenmiller purchased four dozen new holdings during the second quarter and added to 16 existing positions. No individual new stock purchase was larger than the 336,300 shares of Alphabet's Class A shares (GOOGL), worth over $120 million on June 30.

Although Druckenmiller sold every share of Alphabet in the first quarter, he repurchased nearly the same amount that he sold in the second quarter. One catalyst could be the stock market's short-lived Iran-war-driven swoon, which provided an (in hindsight) attractive buying opportunity in March and April.

But it's more likely that Alphabet's soaring AI sales compelled Stanley Druckenmiller to mash the buy button.

Google Cloud knocked it out of the park again. They're now at a ~$99B run rate growing 82% YoY. Another MASSIVE jump in YoY growth

Quarterly YoY growth trends below $GOOG pic.twitter.com/9pAJvuajmh

-- Jamin Ball (@jaminball) July 22, 2026

Alphabet's Google Cloud, the world's No. 3 cloud infrastructure services platform, was steadily growing in the mid-20% range before incorporating generative AI and large language model capabilities. Since integrating these AI solutions into its platform, AI sales have gone parabolic. Google Cloud's second-quarter sales jumped 82% from the prior-year period.

Duquesne's billionaire investor likely also appreciates Alphabet's sustainable moat. While all eyes seem to be on Google Cloud and the AI infrastructure build-out, it's important not to overlook Google's sheer dominance, which accounted for 91% of internet search traffic in July. Between Google and streaming platform YouTube (the second-most-visited social site on the planet), Alphabet sports top-tier ad-pricing power and can generate mountains of operating cash flow.

Sean Williams has positions in Alphabet. The Motley Fool has positions in and recommends Alphabet and Micron Technology. The Motley Fool has a disclosure policy.