Leaving the European Union without a deal in 2019 could cost Britain almost half a million jobs, a report found as London’s key finance industry vacancies also plummeted the most in three years.

Failure to stitch up a deal also means Britain could see around 50 billion pounds ($68 billion) in reduced investment by 2030, according to the report commissioned from Cambridge Econometrics by London Mayor Sadiq Khan. The forecast modeled five different Brexit scenarios, from the hardest to the softest form of Brexit, and broke down the economic impact on nine industries, from construction to finance.

The report was released hours after recruitment firm Morgan McKinley published a survey showing job vacancies in London’s finance industry fell 52 percent in December, the most in three years. There was also a 37 percent decline in job openings year-on-year, underscoring the looming “Brexodus” from the City, the company said.

“In December, the City is abuzz with holiday parties, not hiring, so a drop is to be expected,” Operations Director Hakan Enver said in the report, published Thursday. “But for it to be such a seismic drop is alarming.”

May’s Bankers

In the worst-case scenario in the Cambridge study, Prime Minister Theresa May would fail to secure a two-year transition to ease the passage for businesses, a situation that in London alone may create 87,000 fewer jobs and usher in 10 years of lower growth, Khan’s office said. Negotiations with the EU will resume in March, with the status of banks the new battleground of trade discussions.

May said she had not read the report, adding: “I am confident that we will be able to achieve a good deal, and I’m very clear that that is what we are working for.”

Every Brexit outcome analyzed would damage the U.K. economy, but the more distance Britain puts between its current and future trading arrangements with the EU, the worse things got.

“It’s crucial the government understands the consequences of each scenario they’re considering with the EU,” Khan told BBC Radio 4’s ‘Today’ show. “I want them to choose the best outcome for jobs, for investment and for economic output.”

The timing of the report is unfortunate for the premier, who’s meeting later Thursday with city financiers from companies including Goldman Sachs Group Inc., HSBC Holdings Plc and the London Stock Exchange Group Plc to discuss safeguarding their interests post-Brexit. The study said that in a no-deal hard scenario, the industry that fares the worst will be financial and professional services, with as many as 119,000 fewer jobs nationwide.

Morgan McKinley cited firms’ frustration at the lack of progress in carving out a Brexit divorce agreement and said that a lot of good news—such as an increase in the number of skilled-worker visas being issued—was being overlooked in the confusion. Goldman Sachs, Deutsche Bank AG and Bank of America Corp. are all said to be moving operations away from London in favor of cities such as Frankfurt and Paris in case of a no-deal departure.

The report commissioned by Khan is also likely to be embarrassing for May after Brexit Secretary David Davis confessed last month that the government hasn’t conducted a detailed analysis of the impact of Brexit scenarios on different sectors of the economy. A series of much-talked about documents that Parliament insisted on seeing turned out to be statements of the obvious.

Khan, a member of the main opposition Labour Party, announced he’d commissioned the report after Davis’s admission. Davis was forced by lawmakers to publish studies that he’d previously described as containing “excruciating detail” on the impact of Brexit on the economy but that lawmakers complained had nothing that couldn’t be found on Wikipedia.

“If the government continues to mishandle the negotiations, we could be heading for a lost decade of lower growth and lower employment,” Khan said in a statement.