SPDR Gold Trust GLD, the world's largest gold-backed exchange-traded fund, said its holdings fell about 0.2% to 982.64 tonnes on Monday. By Nakul Iyer Dec 7 (Reuters) - Gold prices edged lower on Tuesday, weighed down by firmer U.S. Treasury yields and bets the Federal Reserve could tighten policy more aggressively ahead of key inflation data later this week. "Gold should slowly tread lower on the prospect of tighter policy and if CPI comes out hotter than expected, that's only going to lead to a more aggressive Fed being priced in," said IG Markets analyst Kyle Rodda.