Recently my company laid off 20% of it's employees. Several of us have got together an started asking about how our 401(k) plans will be affected. In looking online I came across an article by Ted Benna which claims:

"You should also note that an employer is required to fully vest the benefits of all laid-off employees whenever a large number are terminated due to a business decline, a plant closing, etc. The normal standard is a reduction of at least 20% of all employees."

I have tried to find information to back this up but have not been able to. Has anyone dealt with this situation? Can anyone point me in a direction where I might be able to support this claim?