问题如下：
For a portfolio of illiquid assets, hedge fund managers often have considerable discretion in portfolio valuation at the end of each month and may have incentives to smooth returns by marking values below actual, in high-return months and above actual, in low-return months. Which of the following is not a consequence of return smoothing over time?
选项：
A.Higher Sharpe ratio
B.Lower volatility
C.Higher serial correlation
D.Higher market beta
解释：
D is correct. Illiquidity creates an understatement of the total risk measure; as a result, the Sharpe ratio will be artificially higher. Illiquidity creates trends in returns (higher serial correlation), as market shocks during a month will be partially recorded in two consecutive months. Illiquidity, however, biases the market beta downward.
请问是如何导致高序列相关的？
低相关性是不是因为DATA只保留了质量好的？
