Sam Altman made a bet almost four years before January 2019.

Judge as of 5 January 2019. Find the bet Altman refers to (for example a dated tweet, blog post or recorded wager) and its date. True: the bet was made roughly 3.25 to 4 years before 5 January 2019, i.e. between about early January 2015 and early October 2015. Mostly true: the bet was made 4 to 4.25 years before, or 2.75 to 3.25 years before. Mostly false: a bet exists, but it was made more than 4.25 years or less than 2.75 years before January 2019. False: evidence shows that no such bet was made by Altman, or that the bet he refers to dates from less than about 2 years or more than about 6 years earlier.

Set before the research began.

1. E1 Bubble talk blog.samaltman.com (Sam Altman's blog) · 22 January 2015 Own record

   “The top 6 US companies at http://fortune.com/2015/01/22/the-age-of-unicorns/ (Uber, Palantir, Airbnb, Dropbox, Pinterest, and SpaceX) are currently worth just over $100B.”

2. E2 Bubble talk blog.samaltman.com (Sam Altman's blog) · 22 January 2015 Own record

   “Instead of just making statements, here is a bet looking 5 years out. To win, I have to be right on all three propositions.”

3. E3 bubble - SFist - San Francisco News, Restaurants, Events, & Sports SFist

   “Sam Altman is putting his money, or a chunk of it, right where the”

Altman's blog post "Bubble talk", dated 22 January 2015, sets out a bet: "here is a bet looking 5 years out" (E2), with a January 2015 company-valuation baseline (E1). That is just under four years before 5 January 2019, within the criteria's "true" window of early January to early October 2015. The SFist item (E3) independently says Altman staked money on such a prediction, but it is undated and only a fragment, so the dating rests on the blog post itself.