The investment-advice business is a good business to be in indeed: According to a recent study of all SEC-registered investment advisors, the number of firms, clients and assets under management have all showed healthy growth over the past year. The number of clients served by RIAs grew by 6.8%, or almost two million, to nearly 30 million.

The number of advisor firms jumped 5.3% in the last year — its biggest jump in four years — to a total of 11,473 firms, says the most recent annual joint study by the Investment Adviser Association and National Regulatory Services, pulled from data entered in Form ADV, Part 1, by all SEC-registered advisors as of April 8. Assets grew even faster, with aggregate regulatory assets under management jumping 8.1% to a total of $66.7 trillion, as shown by the study.

This boom is in no small part due to baby boomers, who are now approaching or entering retirement, David Mullins, a financial advisor and founder of David Mullins Wealth Management, tells InvestmentNews. “The great wealth transfer,” in which $30 trillion is expected to change hands over the course of 30 years, is putting all that money in motion, says Mullins, adding that the trend will likely continue.

The study also reveals a concentrated industry: The top 1.1% of SEC-registered advisors, or 128 firms, together manage more than half the total regulatory assets under management, while the remaining 11,300 firms manage 46% of RAUM. On the other hand, the numbers also show an industry where small businesses dominate: 87.9% of all SEC-registered advisors report having 50 or fewer non-clerical staff, while 57.3% have 10 or fewer. And overall, there are now more than 750,000 non-clerical jobs in the industry, an increase of 4.3% since 2014, according to the study.

The IAA/NRS study also provides insight into the client base of RIAs. Nearly two thirds (64.1%) primarily serve one client type. For example, almost one-quarter of all advisors (22.8%) derive most of their RAUM from pooled vehicles other than mutual funds and ETFs. More than one quarter (29%) serve mainly individuals. Almost half of advisors have at least one pension client, but only 2.7% serve mostly pension clients.

The growth of the RIA industry will likely put a damper on the SEC’s plans to expand the number of annual advisor examinations from 10% of all firms to 14%, InvestmentNews writes. As new advisors enter the industry, that number is likely to remain at around 10%, John Gebauer, president of the NRS, tells the publication.