Final answer:
The investment bank that remained independent at the end of 2008 was Goldman Sachs. Lehman Brothers filed for bankruptcy in September 2008, while Merrill Lynch and Bear Stearns were acquired to avoid collapse.
Step-by-step explanation:
At the end of 2008, the investment bank that remained independent was Goldman Sachs. Notably, Lehman Brothers filed for Chapter 11 bankruptcy protection on September 15, 2008, which was a major event indicating the onset of a significant economic crisis. Bear Stearns faced bankruptcy and was sold to JPMorgan Chase in March 2008, and Merrill Lynch was sold to Bank of America in September 2008 to avoid collapse.
Critics had warned of the inherent risks in the financial system due to the health of a few significant banking and investment firms which were largely ignored during times of profitability. The failure of Lehman Brothers highlighted issues such as a lack of oversight by its Board of Directors and the Executive Compensation Committee's focus on short-term gains over substantial risks. The sale of Merrill Lynch and the collapse of Lehman Brothers demonstrated the fragility and interconnectivity of the financial system.