Filed Pursuant to Rule 424(b)(5)
Registration No. 333-248738
PROSPECTUS SUPPLEMENT
(To Prospectus Dated
September 17, 2020)
Up to $15,250,000
Common Stock
We have entered
into an At The Market Offering Agreement, or the sales agreement, with H.C. Wainwright & Co., LLC, or the sales agent, dated as of January 13, 2021, relating to the offer and sale of shares of our common stock. In accordance with the terms
of the sales agreement, under this prospectus supplement and the accompanying prospectus, we may offer and sell shares of our common stock having an aggregate offering price of up to $15,250,000 from time to time through the sales agent.
Our common stock is listed on The Nasdaq Global Select Market, or Nasdaq, under the symbol ACOR. On January 12, 2021, the last
reported sale price of our common stock on Nasdaq was $4.24 per share. You are urged to obtain current market quotations for our common stock.
Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus may be made in sales deemed to be at
the market offerings as defined in Rule 415 under the Securities Act of 1933, as amended, or the Securities Act, including sales made directly on or through Nasdaq, the existing trading market for our common stock, sales made to or
through a market maker other than on an exchange or otherwise, directly to the sales agent as principal, in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing market prices, and/or in any
other method permitted by law. If we and the sales agent agree on a method of distribution other than sales of shares of our common stock on or through Nasdaq or another existing U.S. trading market at market prices, we will file a further
prospectus supplement providing all information about such offering as required by Rule 424(b) under the Securities Act. The sales agent is not required to sell any certain number of shares or dollar amount of our common stock, but it will act
as sales agent on a commercially reasonable efforts basis consistent with its normal trading and sales practices.
The sales agent will be
entitled to compensation at a fixed commission rate equal to 3% of the gross sales price per share sold under the sales agreement. In connection with the sale of the common stock on our behalf, the sales agent may be deemed to be an
underwriter within the meaning of the Securities Act and the compensation of the sales agent may be deemed to be underwriting commissions or discounts. We have also agreed to reimburse certain expenses of the sales agent in connection
with the sales agreement as further described in the Plan of Distribution section beginning on page S-10 of this prospectus supplement.
As of January 7, 2021, the aggregate market value of our outstanding common stock held by
non-affiliates was approximately $46,010,782, which we calculated based on 9,483,236 shares of common stock that were issued and outstanding as of January 7, 2021, of which 9,363,394 shares were held by non-affiliates, and a price per share of $4.9139 on December 2, 2020 (as adjusted for our one-for-six reverse stock split that took effect December 31, 2020). Pursuant to General Instruction I.B.6 of Form S-3, in no event will we sell, pursuant to the registration statement of which this prospectus supplement forms a part, securities in a public primary offering with a value exceeding one-third of the aggregate market value of our outstanding common stock held by non-affiliates in any 12-month period, so long as the
aggregate market value of our outstanding common stock held by non-affiliates remains below $75 million. During the 12 calendar months prior to and including the date of this prospectus supplement, we
have not offered or sold any securities pursuant to General Instruction I.B.6 of Form S-3.
Investing in
our securities involves a high degree of risk. You should carefully consider the risks described under Risk Factors on page S-4 of this prospectus supplement, on
page 5 of the accompanying prospectus, any related free writing prospectus and other information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus, before making a decision to invest in our
securities.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved these
securities or determined if this prospectus is accurate or complete. Any representation to the contrary is a criminal offense.
H.C.
Wainwright & Co.
The date of this prospectus supplement is January 13, 2021.