Giving up all its initial gains, the Sensex at the Bombay Stock Exchange stood 145 points, or 0.8 percent in negative territory, at 19,247 in afternoon deals, a short while ago. Earlier in the morning, however, the Sensex had opened with a good gain of 100 points, or 0.5 per cent, at 19,492, on renewed buying by funds and retail investors. Key stock indies in China, Hong Kong, Taiwan and Singapore had posted modest losses of upto 0. 3 percent, today, as political wrangling continued in the United States over billions of dollars of upcoming tax hikes and spending cuts.