The biggest home loan lender in the US just took a huge hit, a bad sign for the housing and mortgage business.

• United Wholesale Mortgage, the country's largest mortgage lender, dropped 35% in one day and suspended its dividend to hold onto cash.
• It reported a $451 million quarterly loss and had to take a $2 billion emergency cash injection from Oak Tree Capital and the family of CEO Mat Ishbia (who also owns the Phoenix Suns).
• Almost no one is buying homes at today's high rates, so mortgage companies have very little business and are running low on money.
• Some are now warning this could be a "Lehman 2.0" moment, echoing the collapse that kicked off the 2008 crisis.

Outlook: A small bounce is possible, but more trouble is likely for mortgage lenders as home buying stays frozen heading into fall.