Solvency Capital Requirement (SCR)

How is capital requirement for type 1 equities calculated for a long/short equity fund which strategy (written in its documentation) consists in investing long in a portfolio of stocks selected stocks from a given index, and a constant and systematic short future contract position on this index? For instance, with a 90% long position in a basket of 100 stocks selected from the S&P500 index and a 50% short position in the S&P500 future contracts, is the following market SCR formulation correct? SCR long/short fund = 39%*(90-50) This SCR computation relies on the joint hypothesis that (1) future contracts on stock indices meet the requirements set out in Articles 208 to 215 of Commission Delegated Regulation 2015/35, and (2) the market risk of the index is representative of the market risk of the stock portfolio composed of selected stocks from this index.