What: Shares of for-profit education provider Apollo Education Group (NASDAQ:APOL) sank on Tuesday after the company reported disappointing earnings, with enrollment falling by a double-digit percentage. The stock was down about 13.5% at 11 a.m.

So what: Apollo reported quarterly revenue of $681 million, down 14.1% year-over-year and $17 million short of analyst expectations. University of Phoenix accounted for the bulk of the company's total revenue, generating $561 million, down 17.7% year-over-year.

Enrollment in Apollo's schools slumped along with revenue. New degreed enrollment came in at 29,400, down from 33,900 during the same quarter last year. Total degreed enrollment declined by 14.5% year-over-year to 206,900.

Apollo reported EPS of $0.44, down about 28% year-over-year and three cents shy of analyst estimates. The company recorded $90.7 million of operating profit during the quarter, down from $116 million during the same quarter last year. During the past nine months, Apollo recorded an operating profit of $96.6 million, down a whopping 67% compared to the same period last year.

Going forward, Apollo expects full-year revenue between $2.6 billion and $2.62 billion, a 14% decline compared to fiscal 2014. The company expects operating income between $190 million and $200 million, excluding special items, compared to $339 million of operating income in fiscal 2014.

Now what: The deterioration of Apollo's business continued during its third quarter, and with guidance calling for further declines in revenue and profits, there seems to be no end in sight. Apollo's revenue has been declining since fiscal 2011, and its operating profit, which topped $1 billion in fiscal 2010, will have declined by 80% over the course of five years if the company hits its guidance this year.

There's really nothing to like about Apollo's quarter, and there's no sign that any kind of turnaround is taking place. The stock trades at just about 7 times the company's guidance for operating income this year, but with revenue and profits relentlessly declining, investing in Apollo appears to be a risky bet.