Said another way. Where there is an active market for private company shares open only to a limited group (employees, investors and other existing shareholders

Said another way. Where there is an active market for private company shares open only to a limited group (employees, investors and other existing shareholders), potential sellers (employees & investors) have had reasonable opportunity to sell however much they want. Potential buyers, on the other hand, do not necessarily have the opportunity to buy. So if you are relating to the value a company would have a following an IPO, you would expect the value to rise. There aren't many new sellers at the internal market valuation price or lower (they could have sold before at that price).