(Reuters) – British online trading platform IG Group said on Thursday that softer market conditions have continued into the third quarter after it reported a 21% drop in half-yearly adjusted pre-tax profit, sending its shares 8% lower. IG Group, which has been cutting costs by laying off staff, reported adjusted profit before tax of 205.7 million pounds ($261.79 million) for the six months to Nov. 30, due to lower market volatility across a range of asset classes. IG Group offers trading of asset classes such as indices, foreign exchange, stocks, and commodities for its clients on its platform…