General and Administrative Expense: Comparing the three months ended December 31, 2017, to the three months ended December 31, 2018, general and administrative expense increased by 0.1%, from $1.515 million to $1.517 million. As a percentage of total revenue, general and administrative expense increased 2.0 percentage points to 13.0%. The increase resulted primarily from fees paid to the outside distribution service provider for the Hennessy Funds, Quasar Distributors, LLC.
Mutual Fund Distribution Expense: Mutual fund distribution expense consists primarily of fees paid to various financial institutions that offer the Hennessy Funds as potential investments to their clients. When the Hennessy Funds are purchased through one of these financial institutions, the institution typically charges anasset-based fee, which is recorded in “mutual fund distribution expense” in our statement of operations to the extent paid by us. When the Hennessy Funds are purchased directly, we do not incur any such expense. These fees generally increase or decrease in line with the net assets of the Hennessy Funds held through these financial institutions, which are affected by inflows, outflows, and fund performance.
Comparing the three months ended December 31, 2017, to the three months ended December 31, 2018, mutual fund distribution expense increased by 2.5%, from $0.120 million to $0.123 million. As a percentage of total revenue, mutual fund distribution expense increased 0.2 percentage points to 1.1%. The increase was due to changes in the composition of average daily net assets held by financial institutions, with an increased percentage of average daily net assets held in Institutional Class shares as compared to the prior period. A larger portion of mutual fund distribution expense is allocated to us on Institutional Class shares versus Investor Class shares.
Sub-Advisory Fee Expense: Comparing the three months ended December 31, 2017, to the three months ended December 31, 2018,sub-advisory fee expense decreased by 3.5%, from $2.5 million to $2.4 million. As a percentage of total revenue,sub-advisory fee expense increased 2.7 percentage points to 21.0%. The dollar value decrease resulted from decreased average daily net assets of thesub-advised Hennessy Funds, partially offset by fee increases resulting from the amendment to thesub-advisory agreement for the Japan Fund and the Japan Small Cap Fund that became effective February 28, 2018.
Depreciation Expense: Comparing the three months ended December 31, 2017, to the three months ended December 31, 2018, depreciation expense increased by 19.6%, from $0.05 million to $0.06 million. As a percentage of total revenue, depreciation expense increased by 0.2 percentage points to 0.5%. The increase was due to higher fixed asset purchases in the current period.
Interest Expense
Comparing the three months ended December 31, 2017, to the three months ended December 31, 2018, interest expense increased by 3.3%, from $0.30 million to $0.31 million. The increase was due primarily to an increase in the interest rate charged to our loan.
Income Tax Expense
Comparing the three months ended December 31, 2017, to the three months ended December 31, 2018, income tax expense increased by 164%, from a benefit of $2.0 million to an expense of $1.3 million. The increase reflects the significant impact of the 2017 Tax Act on our income tax expense for the three months ended December 31, 2017. During the prior period, the 2017 Tax Act required us to record aone-time,non-cash benefit to income taxes for the accounting remeasurement of our deferred tax liability based on the reduced federal corporate income tax rate. The resulting income tax expense was reduced by approximately $4.2 million. Excluding the impact of thisone-time benefit, our income tax expense would have decreased for the three months ended December 31, 2018, as compared to the prior period, primarily due to the decrease in our net operating income, and secondarily due to the decrease in the federal corporate income tax rate.
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