employees with the External Investment Manager, including their related infrastructure, business relationships, management expertise and capital raising capabilities.
During May 2012, we entered into an investment sub advisory agreement with HMS Adviser, LP (“HMS Adviser”), which was the investment adviser to MSC Income at the time, to provide certain investment advisory services to HMS Adviser. In December 2013, after obtaining required no action relief from the SEC to allow us to own a registered investment adviser, we assigned the sub advisory agreement to the External Investment Manager since the fees received from such arrangement could otherwise have negative consequences on our ability to meet the source of income requirement necessary for us to maintain our RIC tax treatment. Under the investment sub advisory agreement, the External Investment Manager was entitled to 50% of the annual base management fee and the incentive fees earned by HMS Adviser under its advisory agreement with MSC Income. Effective October 30, 2020, the External Investment Manager and HMS Adviser consummated the transactions contemplated by that certain asset purchase agreement by and among the External Investment Manager, HMS Adviser and the other parties thereto whereby the External Investment Manager became the sole investment adviser and administrator to MSC Income pursuant to an Investment Advisory and Administrative Services Agreement entered into between the External Investment Manager and MSC Income (the “Advisory Agreement”). The Advisory Agreement includes a 1.75% annual management fee, reduced from 2.00% previously, and the same incentive fee as under MSC Income’s prior advisory agreement with HMS Adviser, with the External Investment Manager receiving 100% of such fee income (increased from 50% previously).
In April 2014, we received an exemptive order from the SEC permitting co-investments by us and MSC Income in certain negotiated transactions where co-investing would otherwise be prohibited under the 1940 Act. During December 2020, we received an amended exemptive order from the SEC permitting co-investments by us, MSC Income and other funds advised by the External Investment Manager in certain negotiated transactions where co-investing would otherwise be prohibited under the 1940 Act. We have made co-investments with MSC Income and the Private Loan Fund (as defined below), and in the future intend to make co-investments with MSC Income, the Private Loan Fund and other funds advised by the External Investment Manager, in accordance with the conditions of the order. The order requires, among other things, that we and the External Investment Manager consider whether each such investment opportunity is appropriate for us and the External Investment Manager’s advised clients, including MSC Income, as applicable, and if it is appropriate, to propose an allocation of the investment opportunity between such parties. Because the External Investment Manager may receive performance-based fee compensation from funds advised by the External Investment Manager, including MSC Income and the Private Loan Fund, this may provide the Company and the External Investment Manager an incentive to allocate opportunities to other participating funds instead of us. However, both we and the External Investment Manager have policies and procedures in place to manage this conflict, including oversight by the independent members of our Board of Directors.
The External Investment Manager launched its first private fund, MS Private Loan Fund I, LP, a private investment fund with a strategy to co-invest with Main Street in Private Loan portfolio investments (the “Private Loan Fund”), in December 2020. The External Investment Manager entered into an Investment Management Agreement in December 2020 with the Private Loan Fund, pursuant to which the External Investment Manager provides investment advisory and management services to the Private Loan Fund in exchange for an asset-based fee and certain incentive fees.
The External Investment Manager earned base management fee income of $4.6 million and $2.3 million during the three months ended September 30, 2021 and 2020, respectively, and $12.7 million and $7.2 million during the nine months ended September 30, 2021 and 2020, respectively. During the three and nine months ended September 30, 2021, an insignificant amount of incentive fee income was earned, while no incentive fee income was earned in the three and nine months ended September 30, 2020.
We allocate certain expenses to the External Investment Manager pursuant to the sharing agreement between it and MSCC. Our total expenses are net of expenses allocated to the External Investment Manager for the three months ended September 30, 2021 and 2020 of $2.7 million and $1.9 million, respectively, and for the nine months ended September 30, 2021 and 2020 of $7.7 million and $5.3 million, respectively. The total contribution of the External Investment Manager to our net investment income consists of the combination of the expenses allocated to the External Investment Manager and the dividend income earned from the External Investment Manager. The total contribution to our net investment income was $4.2 million and $2.2 million for the three months ended September 30, 2021 and 2020, respectively, and $11.6 million and $6.7 million for the nine months ended September 30, 2021 and 2020, respectively.