Conversation so far:
Was he an owner of the Dallas Mavericks?
Cuban purchased a majority stake in the NBA's Dallas Mavericks.
Did he make good money on them?
CANNOTANSWER.
Was there any controversy around this?
In May 2010, H.
Ross Perot, Jr., who retained 5% ownership, filed a lawsuit against Cuban, alleging the franchise was insolvent or in imminent danger of insolvency.

Question: What was Cuban's response?
Self-contained rewrite: What was Cuban's response to  H. Ross Perot, Jr., who retained 5% ownership, filing a lawsuit against Cuban, alleging the franchise was insolvent or in imminent danger of insolvency?