The fund is actively managed; fund managers will consider the best possible outcome for the fund and thus assets may be split across multiple exchanges, or be on a single exchange, at any given time.
Only reputable exchanges are used (e.g. Bitfinex, Poloniex, Liquid, Binance). This is dynamic. The fund managers may also switch between USD and other 'stablecoins' for the best possible returns. These elements are highly variable.