In 2019, Acumen raised $26.7 million in philanthropic capital, a decrease of 27.2% from 2018. Of the $26.7 million, $3.7 million represents grants to fund our Pioneer Energy Investment Initiative which seeks to bring off-grid energy solutions to the world’s poor. Acumen recognized non-cash revenue of $2.8 million, mostly in the form of donated legal services, primarily to support our investing work.
We received $0.4 million in interest income from portfolio loans and recorded a provision of $4.0 million for portfolio investment losses. Acumen carries our program investments at cost, and we lower these valuations when impairment exists. We review our portfolio of assets on an annual basis and apply a consistent valuation philosophy across the companies in our portfolio. Because we carry these investments at cost, we do not mark up our equity investments to fair market value, even when subsequent funding rounds imply an increase in the holding value of our investments. Any increase in value of equity investments would be recognized as realized gains or profits upon exit.
Operating expenses represents all the direct expenses related to a) the running of Acumen programs as well as our management, general, and fundraising costs, b) Technical Assistance grants awarded to our portfolio companies, and c) sub-awards to third-party collaborators in service of certain grant-funded work. They do not reflect any of our investments in our portfolio companies. Total operating expenses for 2019 were $28.8 million, a 21.4% increase compared to the prior year. Donated services expenses (a direct offset to In-kind contributions) comprise $2.8 million. Our increases reflect growth in a number of our program areas including our Portfolio team, our Leadership programs, and our Acumen Academy course offerings. Total Technical Assistance grants for 2019 were $0.7 million of the total, and sub-awards for 2019 represent $2.4 million of total operating expenses.
Program work constitutes 79% of our total expenses. Portfolio expenses were $11.1 million, representing the cost of sourcing, due diligence, planning and the execution of new and follow-on investment disbursements (which totaled $15.4 million), as well as managing our active portfolio of 93 companies. Outreach, Impact and Communications expenses were $5.6 million, representing our work in measuring and reporting our investment performance (both financial and non-financial), and in the research and sharing of our insights gleaned from our programmatic work. Our Leadership program costs increased by 280% in 2019 with expenses of $6.1 million. This increase is primarily driven by a categorization change: We shifted +Acumen from “Outreach, Impact, and Communications” to “Leadership” in preparation of launching Acumen Academy. Fundraising costs and Management and General expenses accounted for $6.0 million, which included expenditure to improve organization efficiency and effectiveness.