London stock markets closed lower at the end of trade on Monday on fears of a US debt default. The FTSE 100 index of top shares was down 0.16 percent at 5,925.26. Lloyds was the most traded stock of the day with 144 million shares changing hands, followed by the Royal Bank of Scotland (RBS), which saw 81 million shares switch owners. Miner Fresnillo was the best blue-chip performer, rising 2.86 percent (49 pence) to finish at 1729. It was followed by Weir group, which rose 2.55 percent (55 pence) to close at 2210. Barclays led the losers, slipping 4.44 percent (10.65 pence) to close at 228.9. It was followed by Lloyds, which was down 4.30 percent (2.03 pence) to finish at 45.10. On the currency markets, a pound was worth 1.628 dollars and 1.1344 euros at 1654 GMT.