RE: Earnings result of writing up value of investmHey Goldblack,
Typically, investments in private companies only change value upwards when a 3rd party makes a significant investment at a higher price. For example, if I buy 1000 shares in a private company for $1000, and then you buy 1000 shares for $2000, the value of my shares would typically be valued at $2000 after your purchase.
Investments in private companies can change downwards when management and/or the company's auditors feel a discount needs to be applied to an investment based on whatever factors they determine, such as missing targets or a change in the market.