David Tittsworth, who led the Investment Adviser Association for 18 years as president and CEO and was a key player in fighting for issues important to registered investment advisors, died Wednesday at age 66 from multiple myeloma, a type of blood cancer.

“David will be remembered as a passionate, dedicated, articulate, and effective advocate for the investment advisory community and for the importance of fiduciary advice,” IAA president and CEO Karen Barr said in a statement. “Our organization – indeed, the entire investment advisory community – owes a great debt of gratitude to David.”

Tittsworth retired from the IAA in 2014, and in 2015 joined Ropes & Gray as a counsel in the firm’s investment management practice in Washington, D.C., where he provided advice to asset management firms on the regulatory and legislative landscape.

“David had a truly impressive career, and was known as one of the foremost experts on securities law and policy issues relating to the investment management industry,” said Bryan Chegwidden, Ropes & Gray partner and global asset management group head.

In a conversation with Tittsworth at the time of his IAA retirement, he recalled some of the highlights of his tenure with the organization such as his 2012 testimony in front of the full House Financial Services Committee that helped defeat legislation that would’ve authorized the creation of a self-regulatory organization for RIAs.

He also pointed to the collaborative effort with other industry groups that created the electronic filing of Form ADV, which was phased in over a number of years.

But he noted that he left the IAA with at least one thorn in his side. “The fiduciary duty debate is probably the issue that continues to vex me . . . brokers and insurance agents have successfully lobbied people at the SEC and on Capitol Hill that imposing a fiduciary duty will deprive retail investors of choices they have,” he said. “I think lost in the debate, and what we and others point out, is that investors are confused and that many options on the broker and insurance side involve compensation that amounts to conflicted advice and isn’t properly disclosed.”

Tittsworth got his undergraduate and law degrees from the University of Kansas, and later worked at private law firms and in the public sector. He worked on Capitol Hill as counsel of the House Commerce Committee prior to joining the IAA in October 1996 when it was still called the Investment Counsel Association (it became the IAA in 2005) and had two people in New York and served 200 member firms with aggregate assets under management of $1 trillion.

He moved the operation to Washington, D.C., and it had more than 500 member firms managing more than $12 trillion by the time he left the organization. The IAA now serves more than 650 member firms managing more than $25 trillion.

“David leaves behind a distinguished and successful legacy,” Barr said. “The trade association he built continues to grow and thrive, just like the community it represents. David will be warmly remembered and deeply missed.”