There is a lot of hope in your post.
Investors will just move money to another country and there are enough who have much better grow rates. (China / India).
Or entities who will bet on the downfall of the U.S and there will be countries who have a high interest in this.
On Monday you can short every major company the downfall will be significant.
This will be very interesting to watch the next world recession is on our doorsteps.
That's probably because the market thought they hit rock bottom. Markets like uncertainty less than bad news, so they are much happier knowing about the downgrade.
p.s. To your earlier point, the '40 ACT details investment requirements for Money Market Funds [can't think of them now, but you are right, there are numerous statutory requirements related to the grade of security certain bodies may invest in]:
On Monday you can short every major company the downfall will be significant. This will be very interesting to watch the next world recession is on our doorsteps.
Money does not care who you are or what you do.