(Bloomberg) -- Stock sales are reaping a windfall for the world’s richest shareholders.Corporate insiders including Amazon.com’s Jeff Bezos and Google co-founder Sergey Brin have ramped up stock sales recently, cashing in on a 14-month long bull market that’s helped boost fortunes to the tune of trillions.U.S. public company insiders offloaded shares worth $24.4 billion this year through the first week of May, with about half sold through trading plans, according to data compiled by Bloomberg. That’s almost as much as the $30 billion total they disposed of in the second half of 2020.Large shareholders frequently sell stock in planned intervals, often through pre-arranged trading programs. Yet the prolonged rally in equities markets has made the value of these disposals, whether planned or opportunistic, strikingly high.There are multiple reasons an investor of any size might be motivated to sell. After the pandemic-defying rally, valuations are increasingly under pressure from rising inflation. Investors are wary the post-Covid recovery could prompt tightening measures from the Federal Reserve. And President Joe Biden’s proposed tax hikes -- including a near doubling of the capital gains rate -- have created uncertainty.Bezos, EllisonWhatever the reason, the sales are flooding the market with yet more liquidity, the consequences of which will ripple through philanthropy, the art market, real estate and other niches.Bezos has sold $6.7 billion worth of Amazon shares this year. While a relative pittance for the world’s richest person, it’s more than two-thirds the value of shares he sold in 2020. Larry Ellison unloaded 7 million Oracle shares in the past week for total proceeds of $552.3 million. Charles Schwab has sold $192 million worth of shares of his eponymous brokerage this year.Brin, who has signaled that he intends to sell as many as 250,000 Alphabet Inc. shares, has disposed of $163 million worth of stock in recent days, his first sales in more than four years, filings show.Mark Zuckerberg and his charitable foundation, the Chan Zuckerberg Initiative, meanwhile, accelerated their sales of Facebook stock in the fall. Zuckerberg or his charity has divested shares at a near-daily clip since November, for a cumulative total exceeding $1.87 billion.The surging markets have exacerbated the concentration risk of the single-stock-dominated fortunes typical of many tech billionaires, said Thorne Perkin, president of Papamarkou Wellner Asset Management.“From a portfolio-management perspective, it makes sense to spread it around,” he said.Covid EconomyAlso among the biggest sellers are some noteworthy beneficiaries of the Covid economy. Zoom Video Communications founder Eric Yuan and used-car retailer Carvana Co.’s Ernest Garcia II have together received more than $1.75 billion from stock sales since March 2020, according to the Bloomberg Billionaires Index. George Kurtz, chief executive officer of cybersecurity firm CrowdStrike, has sold shares worth at least $250 million over that period.Zoom founder Yuan -- the poster child, in many ways, for the coronavirus economy -- has stepped up his sales this year as the firm’s share price slumped. In 2020, he typically offloaded about 140,000 shares a month through a trading plan, which generated more than $350 million over the course of the year.Since March, he’s sold almost 200,000 shares a month on average, yielding him about $185 million. He also donated more than a third of his stake in the San Jose-based company as part of “typical estate planning practices,” according to a spokesman. Some of the cash from his share sales fund donations to unspecified “humanitarian causes.”(Updates with Charles Schwab’s sales in seventh paragraph.)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.