Citigroup (C  ) is preparing to place un-exempted, unvaccinated workers on leave this Friday, with any remaining unvaccinated by the end of the month to be terminated. The move aligns with Citigroup's current vaccination policy, which was put in place in October.

The policy presents one of the most stringent set of vaccination requirements in effect on Wall Street. Goldman Sachs (GS  ) has relegated some unvaccinated employees to telecommuting, a practice that Morgan Stanley (MS  ) and JP Morgan Chase (JPM  ) have also instituted. Currently, no other big banks have plans to dismiss unvaccinated workers.

Citigroup's policy allows for exemptions in some instances. The company's policy provides for Citigroup human resources to "assess all requests for religious, medical or any other accommodation required by state or local law on a case by case basis," according to Citigroup HR Head Sara Wechter.

The Biden Administration's sweeping vaccine mandate is currently facing intense legal scrutiny, with Supreme Court justices hinting at the executive order being an unconstitutional overreach. However, for private businesses, courts appear to be much more supportive of vaccine mandates.

Citi's strict policy is closely similar to United Airlines (UAL  ), which survived a legal challenge in the District Court of Texas. The court dismissed the argument of the company's mandate putting workers in an "impossible position," asserting that by providing alternative options, workers hadn't been forced to accept a vaccine.

The apparent support by courts makes vaccine mandates at least legally tenable, although many companies still appear reluctant due to potential labor market blowback. Retail and food service chains, for example, have voiced concerns that stringent vaccine requirements could further reduce the shrinking pool of low-wage workers. White-collar employers such as JP Morgan Chase and Goldman Sachs appear willing to apply limited pressure but reluctant to push mandates too far as firms attempt.

The announcement might have contributed to Citi's stumble at the market Monday, with the firm dropping 0.50% below Friday's close within the first half-hour of trading. Shares recovered 0.85% to help Citi squeak by just over its previous closing price.