Anglo American has overtaken its mining rival Glencore in the race to the bottom. Yesterday it became the worst performer on the London Stock Exchange so far this year - a day after announcing a restructuring plan as it battles the collapse in commodity prices.Shares in Anglo American have nosedived by 76.5% since January. Switzerland-based Glencore has lost 74.65% across the same period.Since Monday almost £1-billion has been wiped off the value of Anglo after it said it would slash its workforce, suspend its dividend until the end of next year and trim an extra $1-billion from capital expenditure.However, as the market began to digest its plans to overhaul the business, the stock on the FTSE 100 index of leading shares fell by a further 14% yesterday morning.Investors continued to pile out of the stock as brokers issued a slew of bearish notes and slashed its target price.Myles Allsop of UBS cautioned that Anglo's "material restructuring" is not enough to ease balance sheet concerns.Describing the restructuring plans as "ambitious", the investment bank thinks prices for Anglo's key commodities will remain subdued over the next few years, with iron ore and copper set to move into oversupply and coal already oversupplied.But it also believes there is some potential for a recovery in diamonds and platinum.Nick Hatch, a Canaccord Genuity analyst, said Anglo's challenge "remains substantial", despite its heightened urgency to deliver on its restructuring plans."When commodity prices recover, the share price recovery could be significant, but in the meantime investors should remain wary."Shares in Glencore came under severe pressure on September 28, when they plunged by almost 30% after Investec warned the stock could soon be worthless.The commodities trader and producer has cancelled its dividend. Top 10 FTSE 100 fallers this year:1. Anglo American (76.5%)2. Glencore (74.65%)3. BHP Billiton (44.83%)4. Standard Chartered (44.63%)5. Antofagasta (43.77%)6. Pearson (37.98%)7. Rio Tinto (37.37%)8. Rolls-Royce (32.76%)9. Weir Group (32.74%)10. Royal Dutch Shell (32.74%)..