 Shares of iRobot Corp. IRBT, 4.07 tanked more than 11 in the extended session Wednesday after the maker of the Roomba robotic vacuum cleaner and other products reported a wider-than-expected fourth-quarter loss and sales fell short of estimates, saying that chip shortages, shipping delays and other supply-chain problems crimped its business. IRobot said it lost 31.5 million, or 1.17 a share, in the quarter, contrasting with a net income of 13 million, or 46 cents a share, in the year-ago quarter. 