Which was a bigger trauma for European stock investors: this summer’s pummeling of Greek banks, or the last month in Glencore Plc? Based on value lost, it’s the latter by far.

As much as $14.4 billion was erased from the mining company’s shares in September — about $4.4 billion more than was wiped out in a Greek bank index in August. Glencore’s unprecedented volatility in the past 10 days is almost double that of the Greek lenders.

After going from a record 29 percent drop on Monday to a record 17 percent gain the next day, the miner yesterday pared its monthly slump to 38 percent.

Glencore stock moved an average of 7.4 percent a day in September. The FTSE/Athex Banks Index, which includes companies such as National Bank of Greece SA and Piraeus Bank SA, rose or fell 6.5 percent daily on average during this year’s tumultuous months.

Stock swings for the past 10 days
Stock swings for the past 10 days

Looking at what’s coming, traders are expecting things to remain volatile for Glencore:

Expectations for Glencore stock swings jump
Expectations for Glencore stock swings jump