Those who worries about current volume on exchanges should read this article.
http://www.coindesk.com/bitcoin-brokers-trade-millions-without-exchange/Trading over the counter offers several advantages over placing an order on an exchange. For one thing, traders get to protect their capital from the effects of price slippage.
Slippage is what can happen when an investor sells a large block of coins on an exchange all at once. If the sell order is large enough, it can cause the price on the exchange to fall as it is filled. As a result, the seller can lose a substantial chunk of the proceeds by the time the entire order is filled.
Just how much of a trade is lost to slippage is difficult to quantify, according to George Samman, a co-founder of BTC.SX and a former portfolio manager at a New York investment firm. In a hypothetical trade where an investor sold 100 BTC on BitStamp at today’s price of about $490, he or she would stand to lose up to 10% to slippage.
“When someone is trying to put a block trade through and there’s not enough takers at a certain price level, then the price keeps dropping as bids keep getting lower and lower,” he said.
Other factors can come into play. Traders could be laying in wait with ‘false’ orders on the exchange to feel for large blocks coming to market. When some of those orders are filled, savvy traders could cancel the rest of their original orders, sensing that a big block is being traded, and quickly place new orders at lower prices
"There are people who put a lot of value in executing a full block of 1,000 or 5,000 coins at once.”
“The problem with OTC trading is that they are private. People get upset about that and they think there is some kind of manipulation going on. But in the markets today, there is less and less volume. Even in the equity markets, institutions are trading with each other and taking trades offline.”
