Anglo American's shrinking market value could eject the global miner from London's blue-chip equity index at the next reshuffle in March, potentially triggering a broader sell-off.
Plunging commodity prices last year shrank Anglo's market capitalisation to $5.6 billion (3.9 billion pounds) as its shares fell 76 percent to record lows in 2015, making it the worst performer in the benchmark FTSE 100 index.
This compares to 31 billion pounds in 2011 and more than 9 billion in 1999, when the stock was listed in London.