As long as the buys are more than the sells the SP should stay at 0.5C. the buyers at 0.5C (2,616,000) will take out the 0.4c ( 3 @ 1,370,000) and pay 0.4c for them then the remaining (2,616,000 - 1,370,000) will be bought at 0.5c if there are sellers (which there are)