WIG-oil&gas is a sub-sector index and its portfolio includes WIG constituents belonging to the ‘oil and gas’ sector. Weightings in the index are the same as in the WIG index portfolio. WIG-oil&gas index base date is December 31, 2005. The initial value was 3560.08 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.