All the major exchanges.
More importantly, fiat exchanges close the doors on new investors.
bitstamp,bitfinex(10000usd input to have an active account),bittrex,cex etc almost everyone is down/closed for new people.
And you expect the price to be high?
No new money in the market all the exchanges basically manipulating everything.
My advise donot sell your bits they want you to loose.Buy if you can

Bithum,a Korean exchange is well known for manipulation allowing wash trading which is illegal.Futures market would have only little impact on bitcoin price.Surprisingly,bittrex also not friendly nowadays and not even responding to its users queries.Poloniex having poor customer support.We could expect only new exchanges to come and provide good service.