A computer glitch at Moody's ( MCO) caused shares of the bond ratings company to plunge Wednesday and sent other financial stocks down as jittery investors began selling. Moody's experienced a problem that caused some complex European financial instruments to be doled out higher ratings than they should have been given, according to Reuters. The error was discovered in early 2007 and the products were downgraded, but the news was never disclosed. The stock collapsed into its largest one-day drop since being spun off from Dun & Bradstreet. It ended the day down $6.99, or 15.9%, at $36.91. Shares of Hewlett-Packard ( HPQ) were down $1.66, or 3.6%, to $44.80 despite the company reporting a 16% growth in its bottom line during the second quarter due to strong performance in international markets. Revenue during the quarter rose to $28.3 billion, from $25.5 billion a year ago, with 70% of sales coming from overseas. H-P had preannounced its results last week when it said it will acquire technology consulting company EDS ( EDS) for $13.9 billion. Washington Mutual ( WM) gave back 4.4% to $9.40 after Moody's downgraded the rating on its covered bonds. This acion follows the recent downgrades of the senior unsecured debt of Washington Mutual Bank. The concern from Moody's is the increased potential exposure of covered bond investors to the risk of a liquidation of the cover pool in a short time frame in the event of a default. Analog Devices ( ADI) lost $1.40, or 4%, to $33.52 after the chipmaker reported its second-quarter results. Net income for the second quarter rose to $133.1 million vs. $125.4 million a year ago. Revenue rose 8.7% to $649.3 million and EPS, excluding items, were 44 cents. Analysts were expecting a profit of 41 cents a share on revenue of $627.2 million. The company reported a gross profit margin of 61%, down from 61.2% in the first quarter.