TD Ameritrade 2018 Annual Report

35 Asset-Based Revenue Metrics We calculate the return on our bank deposit account balances and our interest-earning assets using a measure we refer to as net interest margin. Net interest margin is calculated for a given period by dividing the annualized sum of bank deposit account fees and net interest revenue by average spread-based assets. Spread-based assets consist of average bank deposit account balances and average interest-earning assets, which include client margin balances, segregated cash, deposits paid on securities borrowing and other cash and interest-earning investment balances. The following table sets forth net interest margin and average spread-based assets (dollars in millions): Fiscal Year '18 vs. '17 Increase/ (Decrease) '17 vs. '16 Increase/ (Decrease) 2018 2017 2016 Average bank deposit account balances . . . . . $116,695 $ 93,922 $ 83,706 $ 22,773 $ 10,216 Average interest-earning assets. . . . . . . . . . . . 30,849 25,316 22,652 5,533 2,664 Average spread-based balances . . . . . . . . . . $147,544 $119,238 $106,358 $ 28,306 $ 12,880 Bank deposit account fee revenue . . . . . . . . . $ 1,541 $ 1,107 $ 926 $ 434 $ 181 Net interest revenue . . . . . . . . . . . . . . . . . . . . 1,272 690 595 582 95 Spread-based revenue. . . . . . . . . . . . . . . . . . $ 2,813 $ 1,797 $ 1,521 $ 1,016 $ 276 Average yield — bank deposit account fees. . 1.30% 1.16% 1.09% 0.14% 0.07% Average yield — interest-earning assets. . . . . 4.07% 2.69% 2.59% 1.38% 0.10% Net interest margin (NIM) . . . . . . . . . . . . . . . 1.88% 1.49% 1.41% 0.39% 0.08% The following tables set forth key metrics that we use in analyzing net interest revenue, which is a component of net interest margin (dollars in millions): Interest Revenue (Expense) Fiscal Year '18 vs. '17 Increase/ (Decrease) '17 vs. '16 Increase/ (Decrease) 2018 2017 2016 Segregated cash . . . . . . . . . . . . . . . . . . . . . . . . $ 95 $ 49 $ 15 $ 46 $ 34 Client margin balances. . . . . . . . . . . . . . . . . . . 920 482 436 438 46 Securities lending/borrowing, net . . . . . . . . . . 222 139 141 83 (2) Other cash and interest-earning investments . . 42 22 5 20 17 Client credit balances. . . . . . . . . . . . . . . . . . . . (7) (2) (2) (5) — Net interest revenue. . . . . . . . . . . . . . . . . . . . $ 1,272 $ 690 $ 595 $ 582 $ 95 Average Balance Fiscal Year '18 vs. '17 % Change '17 vs. '16 % Change 2018 2017 2016 Segregated cash . . . . . . . . . . . . . . . . . . . . . . . . $ 6,832 $ 8,282 $ 7,034 (18)% 18 % Client margin balances. . . . . . . . . . . . . . . . . . . 19,812 12,542 11,751 58 % 7 % Securities borrowing . . . . . . . . . . . . . . . . . . . . 925 1,004 932 (8)% 8 % Other cash and interest-earning investments . . 3,280 3,488 2,935 (6)% 19 % Interest-earning assets . . . . . . . . . . . . . . . . . . $ 30,849 $ 25,316 $ 22,652 22 % 12 % Client credit balances. . . . . . . . . . . . . . . . . . . . $ 20,438 $ 16,182 $ 14,669 26 % 10 % Securities lending. . . . . . . . . . . . . . . . . . . . . . . 2,888 2,004 2,084 44 % (4)% Interest-bearing liabilities . . . . . . . . . . . . . . . $ 23,326 $ 18,186 $ 16,753 28 % 9 %