Retirement Clearinghouse, a Charlotte, N.C.-based advisor to plan sponsors, notes the Social Security Administration recently announced it would stop a letter-forwarding program that plan sponsors have relied on to locate participants of orphaned accounts. The IRS made a similar decision.

To address the void left by the government, and to meet the mounting demand of plan sponsors, RCH has launched an Internet-based search service to locate those missing participants. The new service taps national records on address changes, commercial databases, and social media capabilities.

J. Spencer Williams, RCH's CEO, thinks his company has the answer to the mounting issue of orphaned accounts. "This is the most thorough, cost-effective search capability available to plan sponsors today," he said in a statement.

How the market might respond to RCH's service remains to be seen. But to alleviate the growing risk to plan sponsors, the private market is going to have to do more to fill the gaps left by government. Even against the strains on the labor force since the recession, the U.S. maintains an average workforce attrition rate of 23 percent, according to Terry Dunne, a managing director at Millennium Trust, an IRA provider out of Oak Brook, Ill.

"Over the course of three to five years, if you kept everyone in the plan that has left, you'd have more former employees in the plan than actual employees. Plans were never designed to provide benefits to former employees," said Dunne.

Sponsors are required by law to maintain retirement accounts worth more than $5,000 until enrollees reach retirement, even if they leave the company. Fiduciary laws also require sponsors to maintain outreach and educational campaigns to the orphaned accounts. The cost of doing so, seemingly small to each individual account, adds up quickly, leaving dramatic liabilities on balance sheets.