BlackRock announced that it's cutting the expense ratios on 11 of its ETFs. The four equity funds in the group of 11, which combined manage nearly $20 billion, see fee cuts of 1 or 2 basis points, while the 7 bond ETFs see cuts of between 9 and 20 basis points. The full list is here.In the current version of my ETF Power Rankings, CSJ comes in at #8, CIU at #12, CRED at #13 and CLY at #14 in the Corporate Bond ETF category. Expense ratio is a significant factor in the fund rankings. If these fee cuts were implemented in my last update, the funds would rise to #5, #6, #8 and #7, respectively.Over the past year or so, all of the major players - BlackRock, State Street and Vanguard - have been slashing fees on their products in order to win the AUM war.