NEW YORK — Joshua Kushner’s first formal letter to investors reads like the note of a man who has seen the top of the market before. Thrive Capital, the venture firm Kushner founded, published the letter on Aug. 14, disclosing that it is selling part of its OpenAI stake even as it builds a new $215 million position in Amazon — and warning that the AI boom contains the seeds of its own excess.
“The AI opportunity is enormous, but letting excitement erode investment discipline would be a serious mistake,” Kushner wrote, according to people who have reviewed the letter. The sentence is the closest thing to a thesis statement Thrive has ever published, and it comes from a firm whose own gains have been built on the AI trade: its bets on OpenAI and SpaceX have made Thrive one of the most profitable venture firms in history.
The letter is a first for Thrive — Thrive’s first formal communication to its limited partners since its founding — and its contents were chosen carefully. The firm disclosed that it is selling a portion of its OpenAI shares, a decision that will be parsed by every AI investor in the world. OpenAI is Thrive’s signature position, and its largest outside shareholder has begun to take money off the table.
The Amazon stake offers context. Thrive bought roughly $215 million of Amazon shares, a position disclosed in a regulatory filing the same week. Amazon sits at the center of the AI buildout through AWS, its cloud business, and through its investments in Anthropic; for a firm selling private AI exposure, buying public AI exposure is a hedge of sorts — a way to keep the theme while reducing the concentration.
Kushner’s reasoning, laid out in the letter, is that understanding public markets makes Thrive better at private ones. “Many of our growth-stage companies compete with, partner with, or become the next generation of public technology companies,” he wrote. “The more precise our understanding of public markets, the better our judgment will be in private markets.” The argument is polished; the effect is to soften what would otherwise be read as a pure de-risking move.
The timing is loaded. Anthropic is preparing an IPO that could value it at $2 trillion, and OpenAI’s own listing is expected to follow. Thrive’s decision to sell into that window — before the listings, while private-market prices are at their most generous — is either prudent portfolio management or a signal about where the cycle stands, depending on who is reading the letter.
Thrive’s numbers give the letter its weight. The firm’s assets under management have grown to more than $65 billion, roughly triple the level of December 2024, according to people familiar with the letter, with more than half of the growth coming from investment gains rather than new commitments. The OpenAI and SpaceX positions account for much of that appreciation; Thrive’s stake in SpaceX alone has been valued at $2.6 billion.
Kushner’s own stake in the firm has grown in parallel. His personal investment in Thrive’s funds has climbed to roughly $500 million from about $186 million two years ago, and his net worth has more than tripled to an estimated $16.7 billion, according to Forbes. The letter’s warnings about discipline read differently from a founder who has just become one of the richest men in America.
The firm has been expanding beyond its venture roots. In addition to the Amazon stake, Thrive has built positions in public companies including Shopify and Oscar Health, the insurance company Kushner co-founded, and it led a record-priced purchase of a stake in the Los Angeles Lakers. The diversification is visible: a firm that made its name on private AI is now a multistrategy investor with public-market positions and sports assets.
For OpenAI, the letter is a complication. Its largest outside shareholder signaling caution, even in the most diplomatic terms, adds a data point to the IPO narrative that bankers would rather not see. The company’s response has been to emphasize the scale of demand for its shares; Thrive’s decision to sell a slice, the argument goes, is a liquidity move, not a judgment on the company.
Kushner’s warning stands on its own, though. A founder who has ridden the AI trade further than almost anyone, who has more money than almost any of his peers, chose the moment before the industry’s largest IPOs to tell his investors that excitement is the enemy of discipline. Whether he is selling because the market is rich, or selling because he believes in the long-term story and wants liquidity either way, the letter says something about the temperature of the AI market that no valuation model can.
