Looks like root rot due to overwatering. I'd gently remove it from the pot (lay it on its side and slide it out), remove all of the old soil, and take a look at the roots. If they're black and slimy you have a root rot problem. Try that and post pics of what you find. I think that's a money tree (?) so hopefully some experts on that plant will chime in because I don't know how best to bring them back from root problems.

I'd also recommend reading the following post about water retention in container soils: http://forums2.gardenweb.com/discussions/2842847/container-soils-water-movement-and-retention-xxii

It's a long article but worth your time to read.

How long have you had this? The pot looks impossibly small for a stump that size, almost hard to imagine there being enough soil to overwater in that pot. If it's Pachira aquatica, it could have gotten dry enough to lose foliage, or even perish, if there's mostly roots & very little soil in the pot. The pics won't get big enough for me to see much detail.

The condition of that trunk suggests that the Pachira is beyond saving.

I'm not sure how old she is (to reach a trunk this big). I found her on top of a bin, obviously someone wanted to throw her out. I took her home - and that was about 9 months ago.

I'll repot and hopefully that'll breaths life into her.

The roots actually don't look slimy, but thin and soft. It was almost impossible to remove the soil with such soft roots.