Businesses are struggling with debt structure and day-to-day cash flow management, yet the amount of businesses underinsured has grown, Legal and General has reported.
According to the insurer's estimations, the UK currently has a £1.35trn shortfall in business protection.
The data - which researched the assets, shares and profits of businesses and the attitude of business owners - shows a reduction in corporate debt of £41bn, a decrease in key person protection of £21bn and a significant increase in the shareholder protection gap to £255bn.
According to the provider, the biggest factor to account for the change in the protection gap is the increase in the number of limited companies and partnerships without cover.
Its research showed the number of limited companies had increased by 100,000 from 2008, now reaching 1.3m in the UK.
Clare Harrop, head of specialist protection at Legal & General, said: "Businesses have always had to adapt to survive but recent economic pressures have meant that the pace of change has sped up significantly and as a result UK businesses are holding more un-indemnified risk than ever."
L&G's previous research showed banks have not been able to invest in businesses as freely and business owners have worked hard to pay off outstanding debt.
The recent research showed a significant rise in the proportion of more expensive alternative forms of debt, including overdrafts and regular credit card use - from 21% in 2011 to 41% now of the total debt held.
The provider warned: "This increased reliance on short-term debt like credit cards and overdrafts shows the precarious position many businesses could be in if something unexpected happened to an owner or other key person.
"In addition many business owners do not realise that Director Loan Accounts are a debt to the estate, which has to be repaid to the family in the event of death. Almost 70% of businesses had no plans in place to be able to do this."
The study also revealed 30% of business owners did not have any insurance cover in place in the event of a key person dying or becoming terminally or critically ill.
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