A majority of registered investment advisors grew their client base in recent months, and a big chunk of that came from wirehouses and broker-dealers, according to a study from TD Ameritrade Institutional.

The random survey of 500 RIAs found that 68% of respondents said they had more clients during the six-month period through April, and these advisors said 61% of their new assets came from the wirehouse and broker-dealer channels. During the prior six-month survey, 60% of RIAs said they experienced client growth and that 65% came from wirehouses and broker-dealers.

Of those RIAs who reported client growth, they cited the biggest reason for clients switching was their dissatisfaction with the full-service brokerage model (23%). That was followed by the RIA's adherence to the fiduciary standard of care that puts clients' interests first (21%); existing relationships and consolidation of client assets with a particular advisor (19%); lack of trust in the full-service brokerage model (7%); and a wide selection of investment products without the pressure to sell proprietary products.

Among other findings, just 39% of respondents said they have a succession plan in place. Of these, 49% expect to appoint an internal successor and 19% are inclined to sell their practice or merge with another firm.

On the spending front, 71% of RIAs surveyed said they've boosted technology spending and 62% said they've upped their marketing budgets. Additionally, 39% said they're spending more on salaries and bonuses, and 29% are shelling out more for staffing.