"The business owner, for all his personal wealth, also is a plan sponsor, probably a plan sponsor of health and welfare plans and individual participant needs. A 401(k) gives advisors access to sit down and visit and be a resource to participants," Donnelly said. They also can be a 'resource for a participant's family in consolidation of retirement assets and wealth.'"

The Principal recently released a report called "Boosting profitability in the small retirement plan market" to help its client advisors take advantage of the small retirement plan market. According to the report, small defined contribution plans are expected to experience significant growth through 2015, as small business owners seek ways to attract and retain talent, rebuild and diversify personal assets and help employees save for retirement.

"This creates an opportunity for financial professionals who can sell and service small retirement plans efficiently. Each small plan sold generates a steady stream of revenue, creates a wealth of cross-selling opportunities and offers access to highly-qualified prospects, including business owners and executives," Donnelly said.

According to the U.S. Small Business Administration, there are about 28 million small businesses in the United States. These companies represent 99.7 percent of all businesses in the U.S., employ more than one-half of private sector workers, comprise about 44 percent of the total private-sector payroll and were the primary drivers behind new job growth in the U.S. in 2010, adding almost 500,000 net new jobs.

Only 28 percent of companies with 10 to 49 employees offer a 401(k) plan, compared to 79 percent of companies with 200 to 499 employees, according to The Principal report. These companies offer 401(k)s, profit sharing plans, Savings Incentive Match Plan for Employees of Small Employers (SIMPLEs) and Simplified Employee Pension plans or SEPs.

According to The Principal Financial Group report, "Business Owner Market Study: A Balancing Act—Priorities vs. Plans," 10 percent of small business owners plan to add a retirement plan in the next 12 months and over 48,000 small retirement plans are expected to change service providers.

"Since the majority of small business owners rely on financial professionals and consultants for assistance with retirement plans, those who understand and efficiently serve this market will be well positioned to reap benefits," the report said.

Only 10 percent of the more than 330,000 financial professionals in the U.S. focus their businesses on retirement plans and "research shows that the number one reason a plan sponsor selects a service provider is financial professional recommendation, showing the important role financial professionals play with business owners," according to the "Boosting profitability" report.

There is a huge divide between perception and reality in the small retirement plan market. The perception is that most small businesses already have retirement plans, when the reality is that 72 percent of employees working for small businesses do not have access to a retirement plan. Another perception is that employees don't contribute to plans, when 86 percent of employees with access to a plan do contribute, the report said.

"A financial professional who knows how to work with plan service providers and third party administrators to navigate volatile markets and a shifting regulatory environment has the potential to generate a significant stream of revenue from retirement plan assets," The Principal found. It estimated that a typical small business retirement plan could generate $1,500 to $16,000 in revenue a year.

Financial professionals can grow that revenue by cross-selling other services, like supplemental retirement plans, individual financial services, business protection plans and employee benefits plans, like wellness programs and group health, life, disability, dental and vision insurance.

Companies with fewer than 100 employees usually don't have robust HR departments or a general counsel, so most of the decisions fall on the shoulders of the small business owners, Donnelly said. "They need a trusted advisor, so they can outsource, depend or rely on that trusted advisor for everything….Retirement is the universal entrée into small business."