Oracle shares fell $2.98 or 5.29%, to $53.31 in after-hours trading on Wednesday on the results and news.
Oracle posted net income of $2.8 billion and adjusted earnings per share of 81 cents, in line with estimates compiled by FactSet. Revenue came in at $9.2 billion, however, shy of the $9.3 billion analysts had been looking for.
In the same period a year ago, the company posted earnings of 71 cents a share on sales of $9.2 billion. It reported net income of $3.4 billion.
The company said Hurd is taking leave for an unspecified medical condition.
Oracle Executive Chairman Larry Ellison said in a statement that "Oracle has an extremely capable CEO in Safra Catz and an extraordinarily deep team of executives, many with long tenure at Oracle. Safra and I will cover Mark's responsibilities during his absence."
The company also said its board has increased its authorization for share repurchases by $15 billion.
Shares of the data and cloud services provide had risen about 5% since the company last reported earnings on Jun. 19.