Banks, brokers and insurance companies make up 16.8 percent of the S&P 500, almost double the level from 2009 and closing in on technology companies at 17.6 percent…The last time financial shares were the biggest group in the S&P 500 was May 2008, four months before Lehman Brothers Holdings Inc. filed the biggest bankruptcy in American history.The market cap gains come from the strong stock performance – not surprising given the recent earnings gains: (JPM), Bank of America Corp. (BAC), Citigroup (C), Wells Fargo (WFC), and Goldman Sachs (GS) — held $8.5 trillion in assets at the end of 2011, equal to 56% of the U.S. economy, according data by central bankers at the Federal Reserve. In 2006, the figure was 43%. By one measure, using international standards for derivatives and consolidating mortgage securitizations, U.S. bank assets are roughly 170% the size of the entire $15 trillion American economy, according to Thomas Hoenig, vice chairman of the Federal Deposit Insurance Corp So while the comeback of the high and mighty on Wall Street has been great news for stock investors in major banks, the living large U.S. financial sector may not be beneficial to the overall economy. Some economists believe that financialization—the outsized growth of the financial sector relative to overall gross domestic product—may be holding back the American economy. Earlier this summer, Bruce Bartlett at the New York Times outlined the major academic research that casts an unflattering light on the over-sized U.S. financial sector. Here are the major findings.