WASHINGTON — Pushing Congress to act on proposed financial regulations, President Barack Obama is going to the heart of Wall Street today on the anniversary of Lehman Brothers' collapse to outline changes needed to prevent a future crisis like the one that sent the global economy into a tailspin last year.

Obama has called on Congress to pass a sweeping overhaul of how financial institutions behave but has seen slower-than-sought action. Administration officials said the president will use Lehman Brothers as a starting point to again decry a hands-off approach from Washington that enabled irresponsible lending that sent the largest U.S. financial institutions to the brink of collapse and the larger economy to the edge.

White House spokesman Robert Gibbs said the president would focus on "the need to take the next series of steps in financial regulatory reform" — in other words: Congress, stop stalling and get it done.

The speech comes as the same banks that received tens of billions of taxpayer dollars last year to stay afloat are again betting on the same bonds, commodities and exotic financial products that landed them in trouble.

Proposals to better monitor the financial system and to police the products banks sell to consumers have been opposed by lobbyists, lawmakers and turf-protecting regulators. Mergers and sales of banks have consolidated lending power in even fewer hands. And those large firms still bet far more than the capital they have on hand.

Yet regulations have not moved. Much of the legislative motivation in Washington has been consumed by the contentious debate over changes to the health care system.

Five of the biggest banks — Goldman, JPMorgan, Wells Fargo, Citigroup and Bank of America — posted second-quarter profits totaling $13 billion. That's more than double what they made in the second quarter of 2008 and nearly two-thirds as much as the $20.7 billion they earned in the second quarter of 2007.

The failure of Lehman Brothers — the biggest bankruptcy in U.S. history — and the panicky sales of Bear Stearns to JPMorgan and Merrill Lynch to Bank of America transformed Wall Street and gave fewer competitors increased market power.