That was 4.8 per cent above the previous all-time high of $975 billion (US$891 billion) set in August 2009, BGI said.
The global ETF industry had 1819 ETFs, with 3247 listings from 96 providers on 40 exchanges around the world at the end of September 2009.
Meanwhile, Europe had overtaken the United States in having the greater number of ETFs on offer, with 751 trading in Europe compared to 710 in the US, BGI said.
Most ETFs are index funds that are bought and sold like ordinary shares on a stock exchange.
