1
general::
Phrase(s): bottom out
Fig. to reach the lowest or worst point of something. • All my problems seem to be bottoming out. They can’t get much worse. • Interest rates bottomed out last February.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Reach the lowest level, as in The recession appears to have bottomed out. This verbal use of bottom originated in the late 1800s and, with the addition of out in the mid-1900s, tends to be used mostly in the context of trade and finance.
American Heritage Idioms