Profits from ETF

FT.com: "Why are ETFs so profitable when they appear to be so cheap? Annual management fees have been driven down by price wars, which have been particularly fierce in the US. Synthetic ETFs obviously offer scope for profitable derivative trading and collateral management, but the opportunity to extract revenue is less obvious with physical ETFs, being mainly confined to securities lending. Perhaps running an ETF business is at least in part a means of running a securities lending operation, in which case providers should reveal what proportion of stocks in a portfolio are lent, as the associated counterparty risks are material to investors."