Compaq Computer Corp shares gained $3.875 to close at $109 on Tuesday after a report published Monday said that the company, a heavyweight in the desktop market, is challenging Toshiba Corp’s longtime domination of the US notebook market. The newly released data from Computer Intelligence shows that Compaq increased its dealer and retail market share in Q1 1997 to 25.6%, up from 14.7% in the first quarter a year ago. Toshiba remains on top, but has seen its share decline over the same period from 37.8% to 33.3%. Compaq’s year-to-year notebook sales growth stood at 120% when compared to its 1996 first quarter, while Toshiba’s sales rose only 11% in the same time period. Compaq’s unit sales grew 116% in the year to April 1997. Except for a short period in 1995 when IBM was tops in the dealer channel, Toshiba has been the number one notebook vendor in both the dealer and the retail channels for roughly four years.