The blocks as you call them are nothing more than the tailend of orders placed by sellers/buyers and since almost all tend to buy this stock in 1000's the amounts less than 1000 are bought by market makers to complete the orders.. Example 100,000,923 for sale.. The bid come in for 100,000 and the 923 must be taken into position by the market maker to complete the order.. This causes 2 prints.. hank