CEO Pete Kight did his best to sound relatively upbeat after the company posted its latest results, but investors weren't going for it.

The provider of electronic-payment services missed Wall Street's estimates for the fiscal fourth quarter and offered weak guidance, sending its shares plunging 21% in extended trading Tuesday. The stock was lately dropping $9.01 to $34.12, following a loss of $1.37, or 3.1%, in the regular session.

CheckFree had fourth-quarter revenue of $224.9 million, a 12% increase from the same period last year, but analysts surveyed by Thomson Financial were calling for $230.1 million. The company earned $29.4 million, or 31 cents a share, up from $11.9 million and 13 cents a share a year ago.

Excluding items, the company would have earned $36.5 million, or 39 cents a share, unchanged year over year. As with revenue, the result fell short of expectations. On average, analysts wanted to see a profit of 41 cents a share on that basis.

"We are pleased with our fiscal 2006 results," Kight said in a statement. "Year-over-year growth met our targets. In the fourth quarter, our software and investment services divisions reported solid performance. The consumer transaction growth in our electronic commerce division was soft for the quarter, resulting in quarterly growth below our expectations."

For fiscal 2007, CheckFree forecast earnings of $1.58 to $1.62 a share, or $1.90 to $1.94 before items. The company is expecting first-quarter revenue of $226 million to $231 million and a bottom line of 29 cents to 31 cents. Before items, earnings should be 37 cents to 39 cents.

Analysts have projected an adjusted profit of 44 cents and revenue of $236.3 million in the first quarter. The consensus fiscal-year forecast is for earnings of $1.93, excluding items.

CheckFree was the biggest decliner on the INET ECN after closing. The stock's lowest close for the past year was $33.76.