It's very difficult for Bancor's price to increase. I have seen this time and again whenever somebody buys a large chunk of BNT on Bittrex and pushes the price up within minutes, the automated arbitrage bots bring the price down by arbitraging against the smart contract. I don't see how the price will increase.
That's one of the purposes of the Bancor protocol, to prevent spike/crash cycles and instead have gradual rises and falls.