I finally got the dots connected. GSCO is Goldman Sach's Market Maker firm and it is one of the largest.
GS has made a market in APDN thru its GSCO arm.
That makes sense of why they call in on the teleconferences and hog the time.
While Goldman only holds 50k shares in their portfolio, GSCO makes money on the spread in daily trading.
Therefore, they hold a reserve of stock to service the GSCO platform. That enables them to produce big market swings at end of day trading, especially when there is thin volume. You can see how they do this on level II.
Per Wiki:
A market maker or liquidity provider is a company or an individual that quotes both a buy and a sell price in a financial instrument or commodity held in inventory, hoping to make a profit on the bid-offer spread, or turn.[1][2] The U.S. Securities and Exchange Commission defines a "market maker" as a firm that stands ready to buy and sell stock on a regular and continuous basis at a publicly quoted price.[3]
A Designated Primary Market Maker (DPM) is a specialized market maker approved by an exchange to guarantee that he or she will take the position in a particular assigned security, option or option index.[4]