Only one exchange: BITTREX. BITTREX do support the segwit and provides the comfortable situation for the customers and they have also claimed that all of their customers are allowed to hold bitcoin and bcc after first of august
Ok, but will be BCC trade open or just deposit?
neither of these. and don't get your hopes up. many good exchanges are not going to add BCC pair for trading and some of them won't even credit you, your BCC tokens if you keep coins there. at some point in the future if it can generate enough volume (which is unlikely) they may add the pair to be traded. otherwise they won't bother.
read more here:
https://support.bittrex.com/hc/en-us/articles/115000808991