Nearly a quarter of a million Britons aged over 50 have found hidden share certificates when sorting through a friend's or a relative's house after they had died, according to estimates.
Saga Share Dealing, which made the findings, said that lofts, kitchen cupboards and even garden sheds are places where people had discovered share certificates stashed away by a loved one.
Saga estimates that around 226,000 over-50s across Britain have uncovered certificates in this way, after carrying out a survey of 9,000 people in this age group.
But more than one in three (37%) people surveyed said they would not know what to do with a share certificate if they found one.
Saga estimates that 1.6 million people aged over 50 years old have had shares passed down to them from someone else - whether this has been from a will, or they have been given the shares by someone who is still alive, or they have found them after someone has died.
Women were found to be around twice as likely to have inherited someone else's shares than men, which is likely to be partly due to women's longer life expectancies.
One in five (20%) of women aged over 50 who hold shares said they had inherited them, versus on in 10 (10%) men in this age group.
Analysis of Saga Share Dealing data shows that the average value of paper share certificates is around £6,500.
People aged over 50 in Scotland, London, the South East and South West were the most likely to inherit shares, with 15% of people in these areas who hold shares saying they had inherited them, while in the North West were the least likely to have shares passed down to them, with 10% of people there who have shares having inherited them.
In Wales, 12% of share holders surveyed had inherited shares, while in the Midlands 14% of shareholders had done so, in the North East and Yorkshire and the Humber 13% of share holders had done so, while in East Anglia 11% of people with shares had inherited them.
Joanna Fowler, head of share dealing at Saga Personal Finance, said: "Finding share certificates after a loved one has passed away is not as uncommon as you might think.
"We've heard stories of people finding certificates in lofts, kitchen cupboards and even garden sheds and garages. And a lot of the time they didn't even know their relative had shares stashed away."
Here are tips from Saga for what to do if you end up with a share certificate which had belonged to someone else:
:: If you want to check if the certificates have not been replaced before you try to cash them in, call the registrar and not the company whose shares you hold.
:: The name of registrar can usually be found at the top of the share certificate. If the company name has changed or no longer exists then you can call Companies House, who will help you track down the new company name.
:: If you inherit shares and want to keep them you will need to transfer them into your name. You will need a copy of probate to do this.
:: If you want to sell your paper certificates, bear in mind any charges. The fees can wipe out a large chunk of the sale proceeds so it is worth shopping around for the best deals.