请问这道题对于学组合管理的需要掌握吗？

问题如下：

Tom is a very successful entrepreneur. After six years of entrepreneurship, the technology company he founded is now worth $500 million . It is a private company. He is the controlling shareholder and owns 60% of the shares. His only other investment is Apple stock he bought 10 years ago. Apple’s stock price has risen very well over the past decade, which has greatly increased the value of this publicly traded stock position and is now worth $40 million.

Tom recently sought financial advice from Johnson, his private financial advisor. After discussing Tom's personal situation and financial goals, Johnson believes that Tom's current investment portfolio needs to be optimized, and pointed out several important risks and tax-related considerations related to Tom's investment portfolio.

Discuss four important risk and tax-related considerations that are relevant to Tom’s portfolio.

选项：

解释：

Tom’s portfolio consists of two concentrated positions: his ownership share of his technology company and his publicly traded shares in the company of Apple he bought 10 years ago. As such, Tom’s portfolio is not an efficient, diversified portfolio.

Four important risk and tax-related considerations that are relevant to Tom’s portfolio are as follows:

1 The company-specific risk inherent in the concentrated positions

2 The reduction in portfolio efficiency resulting from the lack of diversification

3 The liquidity risk inherent in a privately held

4 The risk of incurring an outsized tax bill that diminishes return if one were to sell part of the concentrated position in an attempt to reduce the other risks