Decline
Decay
Something that declines and retreats from decline is something that's on a decline. It's also decay.
すいたい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
どの専門家も、投資市場の衰退は信用収縮によって誘導されたと口を揃えて言うけれど、それってつまりはどういう意味なの？
All the experts say that the decline in investments was driven by a credit crunch, but what does that mean?