Many Standard Life customers are sitting on shares they might not even know about, the firm has said.
People who have lost or forgotten about their share holdings are the target of a new campaign.
Insurer Standard Life said that it is looking for 200,000 people who have around £184 million of cash and stocks unclaimed between them. This equates to an average entitlement of £863 each, although one individual has even apparently forgotten about 43,000 shares - valued at around £100,000.
The share losses stem from the firm's demutualisation in 2006. Standard Life has already returned around £100 million of unclaimed cash and stocks.
Paul McKenna, assistant group company secretary of Standard Life, said: "This is a very large pot of shares and cash we're looking to find the rightful owners for. Many of these customers might not have realised in the first place that they were entitled to cash or shares from demutualisation.
"Maybe some people haven't checked the paperwork that we've sent to them and simply don't realise they are, or were, a customer of ours; or maybe you've lost a loved one and weren't aware they were entitled to cash or shares. I'd encourage people to keep an eye out for any paperwork that comes through the post."
The move follows the "dormant account" schemes currently being undertaken by banks, in advance of a new law which will oblige all monies left untouched by account holders for over 15 years to be transferred to a central government fund. HSBC, for example, has already identified 17,000 customers of this sort, who between them have £24 million unclaimed.
