SAN DIEGO (AP) — Maxwell Technologies Inc. said Friday that it needs to restate two years of financial results due to errors in how it reported revenue. The company said that it expects the adjustments will lower its previously stated revenue and profits.

Shares of the energy storage and power delivery company tumbled on the news.

Maxwell said that it expects the restatement will decrease its revenue for its 2011 fiscal year by $6.5 million and revenue during the first three quarters of 2012 by $5.5 million by comparison to its previously stated results.

The company's audit committee found errors related to the timing in how it recognizes sales to certain distributors. The investigation found that the company had arrangements with some distributors regarding payment terms on certain sales, but these arrangements had not been communicated to its finance and accounting department. As a result, the timing of the revenue was not accurately recorded.

Because of these errors, the company said its annual report from 2011 and its quarterly reports for all the periods in 2011 and 2012 should not be relied upon.

The company said its audit committee found the errors with assistance of an independent outside counsel and forensic accountants.

Maxwell has fired a number of employees as a result of the investigation and its senior vice president of sales and marketing has resigned. The company plans to file their updated financial reports as soon as possible.

The company, based in San Diego, makes high-voltage capacitors for use in the distribution of electrical energy.

Shares fell 94 cents, or 10.3 percent, to $8.16 in afternoon trading. Its shares have traded in a 52-week range of $5.81 to $19.34.