WIG-chemical is a sub-sector index and its portfolio includes WIG constituents belonging to the ‘chemical’ sector. Weightings in the index are the same as in the WIG index portfolio. WIG-construction index base date is September 19, 2008. The initial value was 3836.10 points. It is an income-based index and thus when it is calculated it accounts for both prices of underlying shares and dividend and pre-emptive rights‟ income.