Hundreds said to have opted to leave Twitter over Musk ultimatum

Hundreds of Twitter employees refused Thursday to sign a pledge to work longer hours, threatening the site’s ability to keep operating and prompting hurried debates among managers over who should be asked to return, current and former employees said.

The number of engineers tending to multiple critical systems had been reduced to two, one or even zero, according to people familiar with the situation who spoke on the condition of anonymity for fear of retaliation.

The crisis came in response to an ultimatum new owner Elon Musk issued Wednesday demanding that employees...