We will require significant additional financing in the future to fund our operations.
Since inception, we have funded our operations primarily through sales of our equity securities, payments received under our collaboration agreements, debt financings, and interest income. As of December 31, 2012, we had received $439.8 million in net proceeds from sales of our equity securities, including $6.9 million in debt we had retired through the issuance of our common stock, $115.0 million in payments from collaboration agreements, $22.4 million in debt financing, and $22.2 million in interest income.
At December 31, 2012, we had $108.0 million in cash, cash equivalents and investment securities compared to $31.0 million at December 31, 2011. We expect to use between $26 million and $30 million of our cash resources to fund our operations during 2013. We expect that our current cash, cash equivalents and investment securities, together with anticipated payments from our existing collaborations, will be sufficient to fund our operations at least into 2015.
We will require significant additional financing in the future to fund our operations.Our future capital requirements will depend on, and could increase significantly as a result of, many factors, including:
� the progress in, and the costs of, our clinical trials, preclinical studies and other research and development programs;
� the scope, prioritization and number of research and development programs;
� the ability of our collaborators and us to reach the milestones, or other events or developments, under our collaboration agreements;
� our ability to enter into new, and to maintain existing, collaboration and license agreements;
� the extent to which we are obligated to reimburse our collaborators or our collaborators are obligated to reimburse us for clinical trial costs under our collaboration agreements;
� the costs involved in filing, prosecuting, enforcing and defending patent claims and other intellectual property rights;
� the extent to which potential rescission rights for redeemable common stock are exercised;
� the costs of securing manufacturing arrangements for clinical or commercial production of product candidates;
� the costs of preparing applications for regulatory approvals for our product candidates; and
� the costs of establishing, or contracting for, sales and marketing capabilities if we obtain regulatory clearances to market our product candidates.
Until we can generate significant continuing revenues, we expect to satisfy our future cash needs through strategic collaborations, private or public sales of our equity securities, debt financings, grant funding, or by licensing all or a portion of our product candidates or technology. In March 2012, we entered into an At-The-Market Issuance Sales Agreement, or ATM Agreement, with MLV & Co. LLC, pursuant to which we could elect to issue and sell registered shares of our common stock having an aggregate offering price of up to $20 million from time to time over a three-year period. As of December 31, 2012, we had raised gross proceeds of $17.7 million from the sale of 5.3 million shares of common stock under the ATM Agreement. For a discussion of potential rescission rights related to our ATM sales, see Item 15 of Part IV, "Notes to Consolidated Financial Statements-Note 7-Stockholders' Equity and Redeemable Common Stock".
We cannot be certain that future funding will be available to us on acceptable terms, or at all. Over the last few years, turmoil and volatility in the financial markets have adversely affected the market capitalizations of many biotechnology companies and generally made equity and debt financing more difficult to obtain. This, coupled with other factors, may limit our access to financing over the near-term future. In particular, any unfavorable development in our pimavanserin program could have a material adverse effect on our ability to raise additional capital.