First, a public company may create a stock that strips out the market wide movements for the purpose of rewarding managers. That is, the management might have done a great job - but the traded stock plummets because the market as a whole plummets. A second interpretation of shadow stock is a phantom stock that is created by a private company (i.e. that does not have stock traded either on exchange or over the counter) again for the purpose of performance evaluation and rewards.
SHADOW STOCK
Meaning of SHADOW STOCK in English
Campbell R. Harvey. Hypertextual finance English glossary. Английский словарь гипертекстовых финансов. 2012