As far as I know, it's about 16,000 BTC. And the network immediately appeared a message to prevent an ambiguous interpretation of this sale.
"Following consultation with cryptocurrency experts, I sold BTC and BCC, not by an ordinary sale through the BTC/BCC exchange, but in a manner that would avoid affecting the market price, while ensuring the security of the transaction to the [greatest] extent possible,"
This is direct quote from Mt. Gox Trustee Kobayashi. As you can see, this transaction can not affect the course of Bitcoin in any way.
This is a good information about mt gox dumping all they possessed in a manner that shall have no effect on the course of the btc price movement but as good as that may sound; do you have any link to proof the authenticity of your claim ?
Mt. Gox from Tokyo has another 180,000 bitcoins for sale, which he is going to put on the market in lots for sale in order to settle with creditors. According to one information, this can happen in September. Therefore, bitcoin can expect hard times. In this regard, it is difficult to predict the growth of bitcoin this year. He can both rise sharply and fall abruptly.