Reading stock market reaction to the shutdown
The stock market is much more worried about the debt ceiling fight, and much of stock market reaction during the shutdown will be forward looking—how the shutdown is thought to be affecting the likelihood of debt limit default.
For instance, the fact the shutdown happened at all is suggestive of a certain level of Republican craziness, making a debt-limit default likelier.
On the other hand, a very unpopular shutdown might make it harder for Republicans to refuse to raise the debt limit.
Either way, it's mostly about the debt limit.
(One can even imagine a scenario where the stock market would react negatively to progress on ending shutdown—if Boehner said he would allow the House to vote on the Senate bill on order to keep their powder dry for the debt limit fight.)
