What happened

Shares of credit bureau TransUnion (NYSE: TRU) are down 11.5% as of 11:58 a.m. ET on Tuesday, according to data from S&P Global Market Intelligence. The stumble follows the release of its second-quarter earnings that met estimates but were undermined by disappointing guidance for the third quarter.

So what

By nearly almost any measure, TransUnion’s second quarter was a winner. The top line of $948 million not only beat revenue estimates of $964 million but was up a hefty 30% year over year. Adjusted, non-GAAP earnings of $0.98 per share merely met analysts’ consensus estimate, although still topped the year-earlier comparison of $0.96 per share.

The forecasted future, however, isn’t quite as compelling. The company believes sales for the quarter underway will roll in between $935 million and $955 million, versus a consensus of $985 million. The analyst community is calling for third-quarter per-share earnings of $1.02, but TransUnion says it’s only on track to earn between $0.89 and $0.95 per share for the three-month stretch ending in September.

And things aren’t apt to improve dramatically in the fourth quarter. The credit bureau anticipates revenue of between $3.75 billion and $3.8 billion for the full year, generating a per-share profit of between $3.70 and $3.85. Analysts, however, had been calling for a top line of $3.84 billion and a bottom line of $3.87. TransUnion’s CEO Chris Cartwright explained within the official corporate report that headwinds for the mortgage lending business are already starting to blow, with mortgage revenue ultimately likely to decline between 30% and 35%.

Now what

The market’s response to the lackluster outlook is understandable, but perhaps unmerited. The stock was already down nearly 30% from September’s high, and it’s still trading within reach of last month’s new 52-week low. This business slowdown was arguably already priced in, and it’s even more so after today’s drubbing. Factor in that analysts are still modeling healthy top- and bottom-line growth for the coming fiscal year, and this steep sell-off is a buying opportunity for long-term investors who can remain patient and stomach a little volatility between now and then.

James Brumley has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.