An announcement by athenahealth Feb. 25 that the company would delay its fourth-quarter 2009 earnings report caused a 12 percent drop in its stock value in one day last week.

That delay, along with speculation that a 2009 accounting error may have benefited company executives, has prompted five law firms to investigate athenahealth on behalf of investors for possible securities violations.

In the Feb. 25 announcement, athenahealth said it would postpone releasing its earnings for the fourth quarter of 2009, “to allow additional time to complete the year-end audit and conduct an internal accounting policy review related to the timing of amortization for deferred implementation revenue.”

Speaking with VillageSoup on March 2, athenahealth spokesman John Hallock stressed that the internal review was initiated by athenahealth and not an outside agency.

Hallock said athenahealth’s new Chief Financial Officer, Timothy Adams, made a decision to change the method of accounting for items that don’t fall under the Generally Accepted Accounting Principles — commonly referred to as non-GAAP items. Hallock said the company had yet to determine whether it would need to restate past earnings or whether there was an accounting error.

“It is what it is,” he said, “and athena is obviously a company that is very transparent in what we do and we’re very open with the financial community … we put a lot of numbers out there about the health of the company.” Hallock said this transparency makes athenahealth more vulnerable to speculation about the company’s practices.

Athenahealth — a Watertown, Mass.-based company with a 225-employee facility in Belfast — has been lauded for its Web-based medical billing system, which purports to be more dynamic and less expensive than traditional software-based systems.

The company’s mission to streamline medical billing has dovetailed with the Obama administration’s push to digitize the nation’s health records, for which the administration set aside $20 billion in 2009. Charismatic CEO Jonathan Bush has made regular television appearances in support of his company. Last month, athenahealth made Fast Company Magazine’s “Fast 50” list of the world’s most innovative companies.

Questions about athenahealth’s accounting first appeared in a Feb. 8 article by Barron’s Senior Editor Jonathan Laing, which included the subheading, “Athenahealth is rightfully admired for its innovative medical-data business. But its recent earnings restatement raises red flags.”

In the article Laing refers to a discovery, made last December, by a Brean Murray Carret analyst named Bret Jones, of an apparent accounting mistake by athenahealth. According to Laing, Jones brought the mistake to the attention of athenahealth management but reported that he was “stonewalled by the company even after he issued a report on Jan. 15 laying out the adjusted earnings overstatement.”

The error reportedly elevated athenahealth’s consensus adjusted earnings forecasts by 8 cents, from $0.52 to $0.60. Laing, in his article, said it “should be noted that company insiders used the strength imparted to the stock by the flawed adjusted profit (the stock has more than doubled from its two-year low hit in late 2008) to unload more than $25 million of stock in the past 12 months. Jonathan Bush, in particular, sold more than $6 million of stock over the period.”

Five law firms have recently announced investigations of athenahealth. The law firm of Roy Jacobs & Assoc. is investigating claims for violations of federal securities laws between Aug. 19, 2009 and Feb. 25, 2010. Howard G. Smith, Dyer & Berens LLP, Finkelstein Thompson LLP, and Holzer Holzer and Fistel announced similar investigations in the past week.

Athenahealth had its initial public offering in September 2007. Over the past year, the company’s stock has climbed steadily from a 52-week low of $23.15 to a peak in January 2010 at $47.82 per share. On March 2, athenahealth stock closed at $37.19 per share.