The gap between iRobot Corp.’s stock price Amazon.com Inc.’s proposed takeover offer was sliced nearly in half Friday as traders grow more confident the deal will get done after UK antitrust regulators approved the combination.

iRobot shares jumped as much as 21% on Friday to $50.94, the most on an intraday basis since August, when Amazon agreed to acquire the Roomba vacuum maker for $61. The surge in iRobot’s stock pushed the deal spread to around $10, down from almost $19 as of Thursday close.

The market is pricing in roughly 75% to 80% odds of the deal succeeding, assuming iRobot stock will drop by $10 to $20 if the merger falls apart, according to TD Cowen merger arbitrage specialist Aaron Glick.

Read: Amazon’s $1.7 Billion iRobot Deal Cleared by the UK (2)

“The deal’s path to closing has become much clearer,” Glick said, noting the UK agency’s decision was very difficult to predict. Some investors were bearish about the situation after the regulator challenged Microsoft Corp’s acquisition of Activision Blizzard Inc, he added.

Roughly 13% of iRobot’s public share float is sold short, according to S3 data.

The transaction is still pending approvals by regulators in the US and European Commission.