Joshua Roberts/Bloomberg News

Credit ratings are sprinkled throughout hundreds of pages of financial statutes and guidelines.

But ever since Standard & Poor’s, Moody’s and other credit rating agencies belatedly sounded the alarms about the subprime mortgage mess, securities regulators have aimed to curb their influence over the financial industry.

On Tuesday, the Securities and Exchange Commission unanimously approved a plan to erase references to credit ratings from certain rulebooks. The agency also adopted a substitute to the ratings, the first of several such changes the commission must enact in the coming months.

“I believe the rules will provide an appropriate and workable alternative to credit ratings,” Mary L. Schapiro, the agency’s chairwoman, said in a statement.

The rules, stemming from the Dodd-Frank financial regulatory law, are part of a broader movement in Washington to crack down on the rating agencies, which awarded rosy grades to dubious investments at the peak of the mortgage bubble.

Dodd-Frank created a laundry list of new regulations for the industry, including proposals to make it easier for investors to sue the agencies. The S.E.C. must also create its own Office of Credit Ratings to police the raters, though the agency has yet to open its doors as it struggles to scrape together the needed money.

The S.E.C. instead prioritized its plans to remove credit ratings from dozens of regulations, some of them decades old. For instance, securities laws require banks and corporations to rely on credit ratings when issuing debt and setting capital levels.

The S.E.C. is not acting alone. Dodd-Frank requires every financial regulator to scrub credit ratings from their regulations. The Federal Reserve on Monday said it identified more than 40 bank regulations that reference credit ratings.

The S.E.C.’s decision on Tuesday centered on longstanding rules that provide companies a shortcut for issuing debt securities. Until now, companies could register certain securities with the S.E.C. through an abbreviated disclosure process if at least one rating agency awarded the securities an investment-grade rating.

Now, the S.E.C. will enforce a new standard of creditworthiness. Companies can dart around lengthy reporting forms, regardless of credit ratings, if they meet one of several qualifications, the agency said.

Companies that issue more than $1 billion of regulated nonconvertible securities within the last three years or have $750 million of outstanding nonconvertible securities will qualify, according to the S.E.C. Firms that are a “wholly owned subsidiary of a well-known seasoned issuer” will also be eligible.

To allay some concerns about the rules, the agency also agreed to grandfather in companies that were previously eligible for the shortened disclosure. The extension will last three years.

Ms. Schapiro said “just about all issuers that currently” qualify for the shortcut would meet the new standards.

The rule drew strong bipartisan support from the agency’s commissioners. Troy Paredes, a Republican commissioner who originally objected to portions of the rule when it was first proposed in February, said it was “meaningfully improved.”

The S.E.C. on Tuesday also adopted new rules that require larger trading firms – including hedge funds, banks and high-frequency traders – to disclose crucial information to the agency. The rule, regulators said, will allow the S.E.C. to keep a closer eye on risky trading tactics that could spark a repeat of last year’s flash crash, when the Dow Jones industrial average dropped roughly 900 points in 20 minutes before climbing back later that day to erase most of the earlier losses.