Shares of former President Donald Trump's media company saw a significant rise on the last day before the US presidential election.

Shares of Trump Media and Technology Group (DJT), the parent company of Truth Social, rose 15% on Monday, with no clear reason for the price increase.

Trump's stock has been extremely volatile since the company went public in March; its price quadrupled in five weeks before falling 41% in the last three sessions.

Traders have used Trump’s stock as a proxy for the former president’s reelection chances. If Trump is reelected, Truth Social could become an increasingly important communication tool, much as the former president used Twitter to spread policy and other information during his administration. If Vice President Kamala Harris wins, Truth Social’s business prospects could fade.

The stock price does not reflect the underlying economic fundamentals of the company's business, which remains small compared to its established competitors such as X, TikTok, and Instagram. The company is facing a cash crunch, and announced that it generated less than $1 million in revenue during the last quarter.

Although polls show the presidential race remains very close, online betting markets have given Trump an edge over Harris in recent weeks, and market analysts attribute Trump's stock rally to the trend in forecasting sites.

As Harris began to gain ground in online betting markets, Trump’s media stocks began to collapse, a sharp drop that wiped $2.4 billion off Trump’s net worth between Wednesday and Friday, erasing the $3.6 billion he had gained the previous month.

Monday's gains added about half a billion dollars to Trump's net worth.

Trump’s election odds on betting sites rebounded slightly on Monday, but it’s not clear that Monday’s stock gains can be attributed to anything in particular. The stocks didn’t necessarily follow the gradual moves of betting markets, the company didn’t make any announcements, and Trump didn’t appear to make any statements that would boost the stock price.

Trump stocks are considered “meme stocks,” speculative trades that can change dramatically for any reason.

The broader stock market was volatile on Monday, but much less so than Trump's media stocks.

The Dow Jones fell 220 points, or 0.5%, the S&P 500 fell 0.1%, while the Nasdaq was slightly higher.