Even when they have a retirement plan, it is likely to be astronomically more expensive than those offered by large companies.
On average, workers in 2015 put 6.8% of their salaries into 401(k) and profit-sharing plans, according to a recent survey.
Assets at firm's Total Return Fund have slipped 70% from its peak in April 2013 to $82.6 billion.
The agency also proposed a rule to permit cities to create their own savings plans.
The lawsuit highlights a friction that exists at financial-services firms that put employees into their own product.