The report, which will be published next year and is titled The Anatomy of a Crisis, also said that businesses should not avoid an apology solely on the grounds that it may lead to expensive and complex legal liabilities, because those may be outweighed by the broader cost of not saying sorry.
James Melville-Ross, a senior MD in FTI's strategic communication's business in London, along with two other colleagues, analysed 100 major crises from across the world in the past 20 years, including oil spills, cyber attachs, plane crashes, product recalls and more.
"Many CEOs instinctively feel that it is right to apologise but some are advised that they should not. The argument against apology is that it is tantamount to an acceptance of guilt and that then opens the door to potential litigation," their report says.
Of the 100 crises studied, there was only evidence of a public apology in 37 cases, and only 16 of those came within two weeks of the public becoming aware of the situation.
Consumer research on six high-profile studies in recent years found that people looked more favourably on swift apologies in cases such as that from Merlin CEO Nick Varney, after the Alton Towers crash last year. Apologies that took far longer, for example from Starbucks over its tax affairs and News UK over phone hacking, were poorly received.
"Simply put, if you're going to say sorry for wrongdoing, say it soon, avoid equivocation and accept responsibility. Otherwise, irrespective of intentions, your apology may fall on deaf ears," the report says.
It goes on to say that across 37 crises in which media coverage had outlined the cost of litigation to the company, their total legal fees ($67bn, £58bn) were half the total market capitalisation lost over the course of the crisis.
The report concludes: "Issuing a swift apology and accepting the fair payout that may follow might allow a company to begin rebuilding the trust and belief that is ultimately required to support a positive valuation more quickly than any other tactic."
Melville-Ross told PRWeek: "There seems to be as much interest these days in how the company responds to a crisis, as in the crisis itself."
He said companies should be "flexible" in their response to any crisis, rather than sticking rigidly to a predefined plan.