The market is falling is it the affect of the upcoming segwit? Or just a normal move in the market in which is the up and down of the price?? Is it ok to hold bitcoins in the exchanger? Can you help me???
Falling or dropping the price value of different altcoins or bitcoin is just a normal situation in trading industry.
Now about your question regarding holding your bitcoin in the exchange site platform, that would be fine as long as the balance is not a huge amount, even you know the the private key, or security it is still not safe, its just my opinion only. Maybe if the exchange is like Bittrex, Poloniex, or bitcoinwisdom, kraken and others you trusted it, well that would depend on you.