Assembly Biosciences Announces Proposed Underwritten Offering of Common Stock INDIANAPOLIS and

Assembly Biosciences Announces Proposed

Underwritten Offering of Common Stock

INDIANAPOLIS and SAN FRANCISCO - July 10, 2018 -

Assembly Biosciences, Inc. (Nasdaq:ASMB) ("Assembly"), today announced that it intends to offer and sell, subject to

market and other conditions, 3,000,000 shares of its common stock in an underwritten public offering. Assembly also intends to

grant the underwriters a 30-day option to purchase up to an additional 450,000 shares of common stock offered in the public offering.

There can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering.

Jefferies LLC, Leerink Partners LLC, William Blair & Company,

L.L.C. and Mizuho Securities USA LLC are acting as joint bookrunning managers for the offering. Robert W. Baird & Co. Incorporated

is acting as lead manager for the offering.

The securities described above are being offered pursuant to

two shelf registration statements (File Nos. 333-208806 and 333-222366), which were declared effective by the United States Securities

and Exchange Commission ("SEC") on January 19, 2016 and January 10, 2018, respectively. All of the shares in the proposed

offering are to be sold by Assembly.

press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be

any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration

or qualification under the securities laws of any such jurisdiction. The offering can be made only by means of a prospectus supplement

and accompanying prospectus, copies of which may be obtained at the SEC's website at www.sec.gov, or by contacting Jefferies LLC,

Attention: Equity Syndicate Prospectus Department, 520 Madison Avenue, 2nd Floor, New York, NY 10022, by telephone at (877) 821-7388,

or by email at prospectus_department@jefferies.com; Leerink Partners

LLC, Attention: Syndicate Department, One Federal Street, 37th Floor, Boston, MA, 02110, by telephone at (800) 808-7525, ext. 6132,

or by email at syndicate@leerink.com; William Blair & Company, L.L.C., Attention: Prospectus Department, 150 North Riverside

Plaza, Chicago, IL 60606, by telephone at (800) 621-0687, or by email at prospectus@williamblair.com; or Mizuho Securities USA

LLC, Attention: Equity Capital Markets, 320 Park Ave., New York, NY 10022, or by email at US-ECM@us.mizuho-sc.com, or by telephone

About Assembly Biosciences

Assembly Biosciences, Inc. is a clinical-stage public biotechnology

company developing two innovative platform programs: an HBV program advancing a new class of oral therapeutic candidates for the

treatment of hepatitis B virus (HBV) infection and a microbiome program developing novel oral synthetic live biotherapeutic candidates

for disorders associated with the microbiome. Assembly's HBV-cure program is advancing multiple drug candidates with the

aim of increasing cure rates in patients with chronic HBV. Assembly's microbiome program consists of a fully integrated platform

that includes a robust strain identification and selection process, methods for strain isolation and growth under current Good

Manufacturing Practices and a patented delivery system, GEMICEL , which allows for targeted oral delivery of live biologic

and conventional therapies to the lower gastrointestinal tract.

Forward-Looking Statements

The information in this press release contains forward-looking

statements regarding future events, including statements about Assembly's expectations regarding the terms of the offering

or completion of the offering. Assembly intends such forward-looking statements to be covered by the safe harbor provisions

contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as

amended. Actual results or developments may differ materially from those projected or implied in these forward-looking statements.

Factors that may cause such a difference include, without limitation, risks and uncertainties related to market and other conditions,

the satisfaction of customary closing conditions related to the offering and the impact of general economic, industry or political

conditions in the United States or internationally. There can be no assurance that Assembly will be able to complete the offering

on the anticipated terms, or at all. More information about the risks and uncertainties faced by Assembly are more fully detailed

under the heading "Risk Factors" in Assembly's Annual Report on Form 10-K for the year ended December 31, 2017, and

its Quarterly Report on Form 10-Q for the quarter ended March 31, 2018 filed with the Securities and Exchange Commission. You should

not place undue reliance on these forward-looking statements, which apply only as of the date of this press release. Except as

required by law, Assembly assumes no obligation to update publicly any forward-looking statements, whether as a result of new information,

future events or otherwise.