Global mergers and acquisitions will drop by over $1.6 trillion over the coming years unless Britain agrees to leave EU under terms that give it access to the single market.

While the decision of Britain to leave EU will reduce takeover activities under any scenario, a disorganized exit marked by difficult negotiations will cause increased economic and political uncertainty as well as a bigger decline in transactions.

This realization comes days after an estimate of business activity recommended that Britain negotiates a new relationship with the European Union since the British economy was weakening at a rather fast pace since the financial crisis in 2009.

The fallout from Brexit will be focused in the U.K. and it would not lead to a crash similar to the one that came after the collapse of the Lehman Brothers at the beginning of the financial crisis. However, it may take up to four years to reach the levels of activity that was predicted if Britain decided to stay in EU.

The vote is also likely to prompt a $240 billion drop in U.K mergers over the ensuing five years. If Britain is unable to discuss favorable terms, the number will increase to $340 billion or about 34%. The drop in the pound’s value since the EU referendum will make U.K assets more attractive regardless of the ongoing uncertainties. Things should recover rapidly if the exit is orderly.

This data was based on the financial modeling conducted by Oxford Economics.

IHK Markit, on Friday, released its newest purchasing manager’s index, a measure of how the British economy responded to the June 23 EU referendum vote.

The index dropped from 47.7 points in early July to 52.4 in June, and this is the steepest fall in history. The figures are on a 100-point scale and has 50 thresholds separating contraction from growth