An anti-dilution provision used to ensure that investors are not penalized when companies are undergoing additional financing or issuing new shares. A narrow-based weighted average takes into account only the total number of outstanding preferred shares for determining the new weighted average price for the old shares. Taobiz explains Narrow-Based Weighted Average The new weighted average price is adjusted for the preferred shareholder, thus providing protection against dilution. The narrow-based method is the most favorable for investors, as it lowers the price of the preferred shares more than other methods.