Uber Technologies Inc's Chief Financial Officer Brent Callinicos is stepping down, the online taxi service's CEO said in an email to investors.

The company has not named a replacement to Callinicos, but Gautam Gupta, "Brent's right hand on Strategic Finance" will be the acting head of the finance division, Chief Executive Travis Kalanick said in the email seen by Reuters.

Callinicos, a former Google Inc (GOOGL.O) executive, will be an advisor to Uber.

"Brent has done a wonderful job here at Uber but has decided that it is time for his next journey, one where his wife and daughter take the front seat," Kalanick wrote in the email.

Callinicos, who joined Uber in 2013, served as treasurer and chief accountant at Google.