A voluminous report on the financial crisis by the United States Senate — citing internal documents and private communications of bank executives, regulators, credit ratings agencies and investors — describes business practices that were rife with conflicts during the mortgage mania and reckless activities that were ignored inside the banks and among their federal regulators.

The 650-page report, “Wall Street and the Financial Crisis: Anatomy of a Financial Collapse,” was released Wednesday by the Senate Permanent Subcommittee on Investigations, whose co-chairmen are Carl Levin, a Michigan Democrat, and Tom Coburn, a Republican of Oklahoma. The result of two years’ work, the report focuses on an array of institutions with central roles in the mortgage crisis: Washington Mutual, an aggressive mortgage lender that collapsed in 2008; the Office of Thrift Supervision, a regulator; the credit ratings agencies Standard & Poor’s and Moody’s Investors Service; and the investment banks Goldman Sachs and Deutsche Bank.

“The report pulls back the curtain on shoddy, risky, deceptive practices on the part of a lot of major financial institutions,” Mr. Levin said in an interview. “The overwhelming evidence is that those institutions deceived their clients and deceived the public, and they were aided and abetted by deferential regulators and credit ratings agencies who had conflicts of interest.”

The bipartisan report includes 19 recommendations for changes to regulatory and industry practices. These include creating strong conflict-of-interest policies at the nation’s banks and requiring that banks hold higher reserves against risky mortgages. The report also asks federal regulators to examine its findings for violations of laws.