 Shares of Big Lots Inc. BIG, 2.41 plunged 21.2 toward a two-year low in premarket trading Friday, after the home discount retailer swung to a surprise fiscal first-quarter loss and sales that fell more than forecast, as gross margin fell amid challenging changes in consumer demand. The net loss for the quarter to April 30 was 11.1 million, or 39 cents a share, after net income of 94.6 million, or 2.62 a share, in the year-ago period. 