Investors punished shares of Interpublic Group ( IPG), one of the world's biggest advertising agencies, after the company delayed the release of its second-quarter financial results. The company attributed the delay to the needs of the board's audit committee. The audit committee was planning to meet Monday, but the get-together was postponed to give the committee time to review the results before Interpublic's management certifies the company's financials, as required by the Securities and Exchange Commission. The audit committee now plans to meet Aug. 12. Interpublic said it will release its second-quarter results on Aug. 13, a week later than originally planned. Shares of Interpublic ended the day down $4.69, or 23.8%, to $14.99 as investors worried about the decision to delay the results. In June, another big advertising concern, Omnicom ( OMC), saw its shares taken apart after questions were raised about its accounting. Omnicom said its books were in order, but since the collapse of energy trader Enron late last year, shareholders have been difficult to soothe when the possibility of accounting missteps arises. Nothing in the Interpublic announcement suggested that accounting issues had surfaced during the second-quarter review.