On Wednesday, the Senate passed a bill that, if made law, could remove scores of foreign companies—mostly Chinese—from U.S. stock exchanges. The forced delisting would strip affected companies of billions in market value and cause a great deal of reputational damage too.

But what happens to shareholders holding stock in a company that is suddenly no longer on the market?

The short answer: nothing.

Shareholders can keep their shares when a company delists and retain their rights as shareholders in the company. The cash value of those shares, however, might be virtually nil.

Investors witnessed this effect on Wednesday when Nasdaq resumed trading in scandal-plagued Luckin Coffee after announcing the company was due to be delisted. Shares in the Chinese coffee chain—which had been suspended since April 7—collapsed 36% Wednesday to less than $3 (about the price of a Starbucks coffee.) At their peak in January, Luckin shares were trading at $50.

The collapse in price, however, suggests that somewhere out there, investors are still looking to buy the company’s shares. Investors might choose to hold on to shares in a delisted company, hoping that the entity will list again someday and regain its share price.

Delisting does not prevent shares from being traded, either, although the mechanisms for doing so are less convenient. Shareholders may buy and sell shares in a delisted company through so-called over the counter (OTC) exchanges—trades made without the oversight of a centralized market, such as the New York Stock Exchange.

Technically, stocks traded OTC are still listed, as the company needs to register with the Securities and Exchange Commission. The requirements for registering to trade as an OTC stock, however, are less strict than those for an exchange “listed” company. The pink sheet “penny stocks” flogged by Leonardo DiCaprio’s character in The Wolf of Wall Street are one popular form of OTC trading.

If a company goes bankrupt, however, its shares in almost all cases will become worthless. Rapid share-selloffs in the lead-up to a delisting can devastate investors too.

According to Bloomberg, there are over 200 firms trading on U.S. stock exchanges at the moment that could be delisted if the Senate’s bill turns to law.

Their removal would decimate retail and institutional investors alike and could shave as much as $1.8 trillion of value from the market. It remains to be seen whether the House and President Donald Trump have the political will to trigger such disruption and effectively cut U.S. investors off from one of the world's few growth markets at a time when the economy is in tatters.