Complex sentence: The Senate version of H.B.1 did zero out the shared responsibility payment, but repealed "versus purchase" sales of stock (see above), requiring sellers of stock in any one company to dispose of shares in the order they were acquired.
Split into simpler sentences: The Senate version of H.B.1 did zero out the shared responsibility payment. It would repeal the taxpayer's ability to designate a sale of stock as versus purchase, requiring sellers of stock in any one company to dispose of shares in the order they were acquired.