A pension fund sues Duolingo over AI course content as the founder sells $42 million of stock
A pension fund's securities fraud suit filed October 7 makes AI-generated course content the fraud theory, while founder Luis von Ahn sold $25.6 million in September and noticed another $16.3 million the same day. The first DAU reading since the suit lands November 3.
Vincent Jiang · 2 min read
A Michigan police pension fund filed a securities fraud suit against Duolingo+0.18% — Duolingo, up 0.18 percent today on October 7, and its complaint reads like an indictment of AI at the production line: Duolingo's "quickly generated AI content" was degrading the product while management attributed growth to "product improvements" that "get improved retention," the suit alleges 1. The class period runs May 2, 2025, to February 26, 2026, and purchasers of Class A stock have until December 7, 2026, to seek lead-plaintiff status 1.
The numbers the complaint hangs on
Daily active user growth fell from 49% in Q1 2025 to 40% in Q2, then 36% in Q3. The suit says Duolingo's own A/B testing showed that added friction, more ads and subscription upsells, was pushing users out, and that management knew it 1.
DAU growth halved in three quarters while the product leaned on ads and upsells
Data
| DAU growth | |
|---|---|
| Q1 2025 | 49% |
| Q2 2025 | 40% |
| Q3 2025 | 36% |
| Q4 2025 | 30% |
When the company reversed course on November 5, 2025, pledging to prioritize user growth over monetization, the stock fell 25% in a day. CFO Matthew Skaruppa resigned on January 12, 2026, alongside preliminary Q4 DAU growth of 30%, and the stock fell another 8.5%. On February 26, 2026, Duolingo guided to material negative impacts on 2026 bookings, revenue and adjusted EBITDA; the stock dropped 14% more 1.
The founder's ledger
The same day the suit was filed, CEO Luis von Ahn filed a Form 144 to sell 110,046 shares worth $16.3 million, exercised from options that day 2. That follows $17.5 million of personal 10b5-1 sales and $8.1 million more by the Luis von Ahn Foundation between September 16 and 24, under a plan adopted June 2, 2026 2. The plan predates the suit, and von Ahn still holds about 3.4 million Class B shares, so this is scheduled supply, not a flight 5.
The founder's supply adds up to about $42 million in three tranches
Data
| Value | |
|---|---|
| Personal 10b5-1, Sep 16-24 | $17.5M |
| Von Ahn Foundation, Sep 16-24 | $8.1M |
| Form 144, Oct 7 | $16.3M |
The other side of the trade
Baillie Gifford publicly named Duolingo a "significant growth opportunity" after the stock's punishment, the bull case now priced against a fraud theory and insider supply 3. Q2 gave dip-buyers cover: revenue rose 18% to $298.5 million, DAU up 23% to 58.7 million 5. The verdict arrives November 3, the first DAU print since the suit 4.
Deepdive
AI-generated from this story and its cited sources. Not investment advice.
