The U.S. Securities and Exchange Commission (SEC) was created by the Securities and Exchange Act of 1934. William O. Douglas (1898-1980). SEC chairman from 1937-1939 and later an Associate Justice of the U.S. Supreme Court, said in September 1937:
   
“As respects the administrative policy, the administrative phase of the commission’s action, we are and we should be, and I think we will continue to be, what I might call ‘the investors’ advocate.’”
 
The SEC has put “We are the investor’s advocate” on its website and several of its publications. Some SEC critics have contended that the SEC answers to many different constituencies and cannot fairly be called an “investor’s advocate.”
 
       
Wikipedia: U.S. Securities and Exchange Commission
The U.S. Securities and Exchange Commission (frequently abbreviated SEC) is a federal agency which holds primary responsibility for enforcing the federal securities laws and regulating the securities industry, the nation’s stock and options exchanges, and other electronic securities markets in the United States. In addition to the 1934 Act that created it, the SEC enforces the Securities Act of 1933, the Trust Indenture Act of 1939, the Investment Company Act of 1940, the Investment Advisers Act of 1940, the Sarbanes-Oxley Act of 2002 and other statutes. The SEC was created by section 4 of the Securities Exchange Act of 1934 (now codified as 15 U.S.C. § 78d and commonly referred to as the 1934 Act).
 
U.S. Securities and Exchange Commission
“We are the investor’s advocate.”
 
Wikipedia: William O. Douglas
William Orville Douglas (October 16, 1898 – January 19, 1980) was an Associate Justice of the United States Supreme Court. With a term lasting 36 years and 209 days, he is the longest-serving justice in the history of the Supreme Court. In 1975, a Time article called Douglas “the most doctrinaire and committed civil libertarian ever to sit on the court.” He was replaced on the Court by John Paul Stevens, and the combination of the tenure of the two justices on the Court stretched 71 years, a seat held longer by two justices than any other.
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In 1934, he left Yale to join the U.S. Securities and Exchange Commission (SEC), having been nominated by President Franklin D. Roosevelt. He became an adviser and friend to the President and SEC chairman in 1937.
 
23 September 1937, New York (NY) Times, “Text of W. O. Douglas’ Statement at Press Conference,” pg. 45:
WASHINGTON, Sept. 22.—The stenographic record of the first press conference of William O. Douglas as chairman of the Securities and Exchange Commission follows:
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As respects the administrative policy, the administrative phase of the commission’s action, we are and we should be, and I think we will continue to be, what I might call “the investors’ advocate.” We have got brokers’ advocates; we have got exchange advocates; we have got investment banker advocates, and we are the investors’ advocate. That isn’t foisting my own economic and social theories and ideas in the picture. You find that within the framework of the three statutes that we presently administer. That is the one fundamental, underlying philosophy of thos three statutes—protection of the investor.
 
21 May 1938, New York (NY) Times, “Address by W. O. Douglas Offering a Plan to Safeguard Wall St. Investors,” pg. 21:
The text of the address delivered by William O. Douglas, chairman of the Securities and Exchange Commission, last night at the dinner of the Association of Stock Exchange Firms, follows:
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Investor Put First
We are first and last the investors’ advocate. But we are also your advocate. A proprietor of a business such as yours can render a high service to his customers and to the nation. WIth full sincerity I can say that if we can help you render that service we will have helped you help our whole national economy. For it must be remembered that your vitality and strength are symptomanic of the health and vitality of all of our financial processes.
 
19 May 1939, New York (NY) Times, “Frank Heads SEC,” pg. 36:
WASHINGTON, May 18.—Jerome N. Frank was elected today chairman of the Securities and Exchange Commission by a three-to-two vote immediately after Leon Henderson had taken the oath as a member of the commission.
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SEC the “Investors’ Advocate”
“SEC’s part of the job relates primarily to investors, to the millions of Americans who put their savings into the stocks and bonds of American industries. SEC has been called the investors’ advocate. Now, you can’t have continued investment without profits, and you certainly can’t have investment without the confidence of investors—without the confidence of the great middle class. And that’s where, as I see it, the SEC comes in. While, to be sure, there are some great self-sufficient industries, not requiring new investors, yet it is undoubtedly true, in the main, that the flow of funds from investors to business and back to investors and to labor and to farmers, in the form of profits and wages, is the life-line of American democracy.”
 
31 October 1979, New York (NY) Times, “S.E.C.” Watchdog 1929 Lacked” by Judith Miller, Pg. D19:
Instead of pursuing its mandate as “the investor’s advocate,” Mr. Seligman argues, the agency, under Mr. Williams, has become more of a neutral arbiter and this less effective.
 
Google Books
Regulating Financial Services and Markets in the 21st Century
By Eilis Ferran and Charles Goodhart
Oxford: Hart Publishing Ltd.
2001
Pg. 223:
“We are the investor’s advocate” is the often cited motto of William O. Douglas, SEC Chairman (1937–9), which features prominently on the SEC website: http://www.sec.gov.
 
5 December 2001. New York (NY) Times, “Watching The Firms That Watch The Books” by Alex Berenson, pg. C8:
Gregg W. Corso, a former senior lawyer at the S.E.C., said the commission had lost its focus. In 1937, William O. Douglas, the third chairman of the commission, said it was “the investor’s advocate.”
 
Today, the commission sees itself as answerable to many different constituencies, including companies that issue stocks and bonds, securities firms and accounting firms, Mr. Corso said. To keep those groups happy, it has allowed accounting standards to slide.
 
OCLC WorldCat record
SEC annual report : “We are the investor’s advocate.”
Publisher: Lanham : Bernan Assn, 2002
Edition/Format:  Book : English
 
OCLC WorldCat record
Editorial The SEC: Still the Investor’s Advocate?
Edition/Format:  Article : English
Publication: CPA JOURNAL, 77, no. 11, (2007): 80
Database: British Library Serials
   
OCLC WorldCat record
The investor’s advocate : how the SEC protects investors, maintains market integrity, and facilities capital formation
Author: United States. Securities and Exchange Commission.
Publisher: [Washington, D.C.] : U.S. Securities and Exchange Commission, [2008]
Edition/Format:  eBook : Document : National government publication : English : [2008 ed.