If a top executive of your company suddenly wasn't able to work, who would take over? Chances are the answer is not clear.

It seems a large number of companies do not have a clear cut succession plan currently in place.

It is the big question facing every company that needs to replace top management or even low level management. Promote from within or reach outside the firm?

Well, a new study found that when it comes to hiring chief executive officers at publicly traded companies, shareholders should urge the board to promote from within.

More than half of companies today cannot immediately name a successor to their CEO should the need arise, according to new research conducted by executive search and leadership consulting firm Heidrick & Struggles and Stanford University's Rock Center for Corporate Governance.

"The lack of succession planning at some of the biggest public companies poses a serious threat to corporate health, especially as companies struggle toward a recovery," said Stephen A. Miles, vice chairman at Heidrick & Struggles in a prepared statement. "Not having a truly operational succession plan can have devastating consequences for companies - from tanking stock prices to serious regulatory and reputational impact."

I have the privilege of assembling our weekly CFO Moves column, so the finding of a new survey that the vast majority of finance chiefs haven't identified their successor doesn't really surprise me. I've seen a lot of press releases stating, "The company is considering both internal and external candidates to fill the position."

Still, the percentage of companies with no CFO succession plan is pretty staggering. The aforementioned poll of 1,400 CFOs by Robert Half Management Resources found that 83 percent have not identified a successor for their position.