Imagine you have a diversified investment portfolio comprised of $50,000 invested in a mix of large-cap, mid-cap, and small-cap stocks, $30,000 in government and corporate bonds with varying maturities, and $20,000 allocated to high-yield savings accounts and money market funds. Over the past year, large-cap stocks returned 12%, mid-cap stocks returned 8%, small-cap stocks returned 15%, the bond portfolio yielded an average return of 6%, and the cash equivalents earned 2% interest. Given this, analyze the performance of each asset class, considering their returns, volatility, and correlation with each other. Additionally, assess how the overall portfolio's performance compares to a benchmark index such as the S&P 500.