Final answer:
Investors who were diversified across industries experienced significant losses because most industries were suffering from weak economic conditions during the financial crisis in 2008-2009.
Step-by-step explanation:
During the financial crisis in 2008-2009, investors who were diversified across industries experienced significant losses because most industries were suffering from weak economic conditions. The recession caused a decline in credit and consumer spending, which in turn affected businesses and led to job losses.
Additionally, the collapse of the housing market and the banking crisis further contributed to the overall economic downturn. As a result, investors across various industries were negatively impacted.