The gap between ABT.WI and ABBV.WI has narrowed and each is now trading at close to 50% of the combined ABT. On E*Trade, it shows that about 4M of the .WI shares have traded today.
I only now realized what you were asking in #msg-82364396 when questioned where the ABT.WI and ABBV.WI shares came from.
When the stock exchange (NYSE in this instance) approves when issued shares for trading, the MM’s receive an initial inventory for liquidity purposes; an equal number of shares is removed from circulation when the “real” shares begin trading (on 1/2/13 in this instance), so there is no permanent change to the share count of ABT or ABBV on account of trading in the .WI shares. In the meantime, the .WI shares work just like any derivative security.