On Thursday, the United Kingdom will vote in a highly charged and long-anticipated referendum on whether the country should exit the European Union, nicknamed “Brexit,” (short for “British Exit”). But it’s not just Britons and Europeans who are invested in the outcome of the referendum: Several American companies are lobbying hard to keep Britain in the EU.

The British American Business Council, which represents American businesses operating in the U.K. and includes the U.K. arm of the U.S. Chamber of Commerce, has warned against a Brexit. A fact sheet on its website describes the U.K. as the “gateway” to the European single market, saying 3 million jobs in the U.K. are dependent on trade with the EU. According to CNN, trade between the U.K. and the U.S. is worth $204 billion, including “$767 million from television programs such as Downton Abbey and Sherlock, $306 million in Scottish salmon, and gin worth $207 million.” A speech this April by the U.K.’s chief secretary of the Treasury noted that “three leading independent surveys all rank London number one” in global finance, and that “well over half” of the £6 trillion of assets in the U.K. are from international banking.

According to the Wall Street Journal, foreign “banks concentrated large chunks of their global operations in Britain” because it allowed them to “save on costs and build economies of scale.” But U.S. banks have threatened to relocate to Amsterdam or other European cities if the U.K. leaves the EU.

Several of the biggest U.S. banks backed up these warnings with hefty donations to the Remain campaign, the lead proponents of Britain staying in the EU. According to the Telegraph, Goldman Sachs and JP Morgan donated £500,000 (about $730,000) to the group “Britain Stronger in Europe” in the period before disclosure was mandated. Citigroup and Morgan Stanley donated £250,000 each, according to the U.K. Electoral Commission’s figures, as did Bloomberg. PricewaterhouseCoopers also donated £7,508.50 to Remain. In total, the U.S. companies donated £757,508.50 in the reporting period, plus £1 million beforehand — that’s about $2,576,000 USD total. In the reportable period, the Remain campaign raised £7,542,652, compared to the Leave campaign’s £14,180,425 (including loans totaling £6 million).

Whether or not these American banks’ warnings of catastrophic consequences for the U.K. economy came from a place of charitable concern for America’s oldest ally, or the desire to protect their own bottom line, it’s clear that they felt it was worth investing a significant sum of money in the Remain campaign.