Nope, not true. When the court accepts the BK filing, a Q is typically added to the trading symbol which immediately downlists to the Pink Sheets or the Bulletin Boards, as assigned by OTCMARKETS. The shares still trade, just not on the NASDAQ exchange. This often happens within a business day or two of the initial PR announcing the intent to file.
As soon as this occurs, Yahoo normally shuts down the message board.
This is what happened during Exide's prior bankruptcy.