Amortization of deferred sales commissions and fund contracts was $40.9 million in the fourth quarter of 2012, a  decrease from $41.1 million in the fourth quarter of 2011 and unchanged from the third quarter of 2012. The trend of lower  amortization expense is consistent with the trend in lower spending on deferred sales commissions in recent years. Interest expense of $6.2 million was recorded for the quarter ended December 31, 2012 compared with $6.8 million for  the quarter ended December 31, 2011 and $6.3 million for the quarter ended September 30, 2012. As mentioned earlier,  the decrease in interest expense from the prior year period reflected lower average debt levels, as discussed under  “Liquidity and Capital Resources.”  As illustrated in Table 7, EBITDA for the quarter ended December 31, 2012 was $178.8 million ($0.63 per share) compared  with $173.6 million ($0.61 per share) for the quarter ended December 31, 2011 and $175.2 million ($0.62 per share) for the  quarter ended September 30, 2012. The 3% year-over-year increase in quarterly EBITDA reflects the increase in average  assets under management offset by the effect of the change in asset mix. EBITDA as a percentage of total revenues  (EBITDA margin) for the fourth quarter of 2012 was 48.2%, down slightly from 48.7% in the last quarter of 2011 and 48.5%  in the prior quarter. The Asset Management segment is CI’s principal business segment and includes the operating results and fi nancial  position of CI Investments and CIPC. The following table presents the operating results for the Asset Management segment: Quarter ended  Quarter ended  Quarter ended  Year ended  Year ended (in millions) Dec. 31, 2012  Sept. 30, 2012  Dec. 31, 2011  Dec. 31, 2012  Dec. 31, 2011 Management fees  $325.8  $318.8  $312.1  $1,277.7  $1,302.8 Other revenue  10.1  9.0  10.2  39.0  45.5 Total revenue $335.9  $327.8  $322.3  $1,316.7  $1,348.3 Selling, general and administrative  $59.6  $57.7  $57.3  $233.3  $235.9 Trailer fees  99.7  97.4  94.3  389.1  394.1 Amortization of deferred sales commissions  and fund contracts  41.6  41.6  41.8  168.1  169.7 Other expenses  0.3  1.1  0.8  2.0  4.1 Total expenses  $201.2  $197.8  $194.2  $792.5  $803.8 Income before taxes  and non-segmented items  $134.7  $130.0  $128.1  $524.2  $544.5 TABLE 8: RESULTS OF OPERATIONS – ASSET MANAGEMENT SEGMENT ASSET MANAGEMENT SEGMENT 31