Less than two weeks after disclosing a plan to dispose of as many as 50 million shares of the company he founded, Bezos has offloaded 24 million shares, worth more than $4 billion. The sales, revealed in regulatory filings, took place over just four trading days. The world’s second-richest person previously hadn’t sold stock since 2021.

Bezos hasn’t explained why he’s selling now, but the timing of when he instituted the trading plan may provide a clue. He announced on Nov. 2 he was moving to Miami from the Seattle region. He adopted a so-called 10(b)5-1 plan on Nov. 8.

Washington state instituted a 7% capital gains tax in 2022 — something Florida doesn’t have — meaning Bezos’s relocation is likely saving him $288 million so far. Because Bezos has only ever bought a single share of Amazon, it’s safe to assume he’s owned the stock since the company was founded and therefore virtually all of their value would be considered capital gains.

Amazon shares were up 13% this year through Monday’s close, the last day on which Bezos sold shares, according to a filing. They slipped 2.2% to $168.64 on Tuesday.

Spokespeople for Amazon and Bezos declined to comment.

A tax bill of $288 million would be a significant windfall for Washington, which raised $855 million from the capital gains tax last year, more than half of which came from just 10 people, according to state officials. 

The tax has received some pushback in the state. Billionaire Ken Fisher in March said he would move his firm from Washington to Texas, criticizing the tax and the court decision that upheld it. A ballot initiative could make its way to voters in November seeking to repeal the levy.