In a US Senate hearing room this week, seven former Washington Mutual executives will speak publicly for the first time about what happened as the giant Seattle thrift careened toward ruin. They will be under oath, and under an intense national spotlight. The Senate’s influential Permanent Subcommittee on Investigations will hold up WaMu as a case study in how high-risk home loans, allegedly made with little concern for the borrowers’ ability to repay, contributed to the financial system’s near-meltdown in the fall of 2008. “The recent financial crisis was not a natural disaster; it was a man-made economic assault,” Sen. Carl Levin, D-Mich., chairman of the subcommittee, said in a statement Friday. “People did it. Extreme greed was the driving force. And it will happen again unless we change the rules.”