Some ports are too small to play SBOs too far out. When players start out, they play one to two weeks out. After they gain some cash, they are able to free up enough to go four weeks, and ultimately get rich enough to afford a year or more ahead. This would be four weeks out, and the majority of small ports still wouldn't be able to afford reaching this far, ignoring certain other SBOs between now and then.
Secondly, some players play on dROI mainly. Again, e smaller and medium sized ports may not have seen good dROI until e adjust to make it worthwhile enough to abandon currently owned SBOs and other stocks until post adjust.
lastly is the question of money available. It cost a lot of money to invest and hold HGAME. Until adjust, that money was not freed up. Smaller ports would have sold everything they owned to buy into the moviestock knowing it was going to pay out big. Now that the money is returned, they have it available again to invest in the SBOs.
So, not surprising at all.