Elon Musk is on his longest stretch without posting on Twitter in nearly five years, a nine-day hiatus that comes in the midst of tumultuous efforts to complete his planned $44 billion deal to buy the platform.

The billionaire chief executive of Tesla Inc. TSLA -1.76%▼ last posted on June 21, marking Thursday as the most extended silence since October 2017. Normally a serial tweeter, he hasn’t gone more than six days without tweeting since January 2018, according to a Wall Street Journal analysis of tweet data. Since then he has taken a few four-day breaks, most recently this past January, the analysis shows.