Big block shareholders often pace the selling of shares for the same reason, but to the flip side, as they are trying to avoid causing a harsh price drop resulting from the dumping of large blocks of shares
creating panic selling as negative speculation kicks in. The same thing, but with positive speculation, will drive the price up if large block purchases occur in quick succession regardless of rising ask price. It usually takes that "big news" to create that much feverish buying pressure. It'll happen, hold your shares a little longer.