2020 and 2019. During the six months ended June 30, 2019, $75.0 million under the Athyrium Credit Facility was outstanding, and remained outstanding during the six months ended June 30, 2020.
Liquidity and Capital Resources
Since our inception, we have incurred significant operating losses. As we commercially launched our first product, INVELTYS, in January 2019, we have had limited revenues to date from product sales and have financed our operations primarily through proceeds from our IPO, public common stock offerings and sales of our common stock under our ATM Offering, private placements of preferred stock, convertible debt financings, borrowings under credit facilities, and warrants.
In July 2017, we completed an IPO pursuant to which we issued and sold 6,900,000 shares of our common stock, which included 900,000 shares sold pursuant to the exercise of the underwriters’ option to purchase additional shares, at a price of $15.00 per share. We received net proceeds of $94.0 million after deducting underwriting discounts and commission of $7.3 million and offering costs incurred in 2017 of $2.2 million.
On August 9, 2018, we filed our 2018 Shelf Registration, under which we may offer and sell up to $250.0 million of a variety of securities including common stock, preferred stock, warrants, depositary shares, debt securities, purchase contracts, purchase units or any combination of such securities during the three-year period that commenced upon the 2018 Shelf Registration becoming effective. Under the 2018 Shelf Registration, we may periodically offer one or more types of securities in amounts, at prices and on terms announced, if and when the securities are ever offered. We initially designated $50.0 million of our 2018 Shelf Registration to be offered under our ATM Offering. There was $18.3 million of securities available to be issued under the 2018 Shelf Registration as of June 30, 2020.
On October 1, 2018, we entered into the Athyrium Credit Facility with Athyrium for up to $110.0 million. The Athyrium Credit Facility provided for a Term Loan A in the aggregate principal amount of $75.0 million, and a Term Loan B in the aggregate principal amount of $35.0 million. On October 1, 2018, we borrowed the entire principal amount of the Term Loan A. We did not satisfy the conditions to draw down any of the Athyrium Term Loan B funds, and as a result, the Term Loan B funds are no longer available. The maturity date of the Athyrium Credit Facility is October 1, 2024, the six-year anniversary of the close. The Term Loan A bears interest at a rate of 9.875% per annum, with quarterly, interest-only payments until the fourth anniversary of the Term Loan A. The unpaid principal amount of the Term Loan A is due and payable in quarterly installments starting at the end of the fourth anniversary of the loan.
On October 5, 2018, we sold 7,500,000 shares of common stock in an underwritten offering pursuant to the 2018 Shelf Registration at a public offering price of $8.25 per share, before underwriting discounts and commissions. In addition, the underwriters were granted an overallotment option to purchase an additional 1,125,000 shares of the common stock at the same public offering price, less underwriting discounts and commissions. On October 11, 2018, the underwriters exercised in full their option to purchase the overallotment shares. The total number of shares sold by us in the offering was 8,625,000 shares, resulting in net proceeds to us, after underwriting discounts and offering expenses, of $66.1 million.
On March 11, 2020, we sold 16,000,000 shares of our common stock in an underwritten offering pursuant to the 2018 Shelf Registration at a public offering price of $7.89 per share, before underwriting discounts, commissions, and offering expenses, resulting in net proceeds of $118.2 million. In addition, the underwriters of the offering were granted the option for a period of 30 days to purchase up to an additional 2,400,000 shares of common stock offered in the public offering at the public offering price, less underwriting discounts and commissions. On April 3, 2020, the underwriters exercised their option and purchased an additional 979,371 shares of common stock at $7.89 per share, before underwriting discounts, commissions, and offering expenses, resulting in net proceeds to us of $7.2 million. The total number of shares sold by us in the offering was 16,979,371, resulting in total net proceeds to us, after underwriting discounts and offering expenses, of $125.4 million.
In connection with the filing of the 2018 Shelf Registration, we entered into a sales agreement with Jefferies, pursuant to which we could issue and sell, from time to time, up to an aggregate of $50.0 million of our common stock in an ATM Offering, through Jefferies, as sales agent. As of December 31, 2019, we had issued an aggregate of