X4 Pharmaceuticals, Inc — Director's Dealing 2017

Nov 20, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Arsanis, Inc. (ASNS)
CIK: 0001501697
Period of Report: 2017-11-20

Reporting Person: ORBIMED ADVISORS LLC (10% Owner)
Reporting Person: OrbiMed Capital GP IV LLC (10% Owner)
Reporting Person: ISALY SAMUEL D (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-11-20	Common Stock	C	19533	—	Acquired	19533	Indirect
2017-11-20	Common Stock	C	252230	—	Acquired	271763	Indirect
2017-11-20	Common Stock	C	328909	—	Acquired	600672	Indirect
2017-11-20	Common Stock	C	114320	—	Acquired	714992	Indirect
2017-11-20	Common Stock	C	653974	—	Acquired	1368966	Indirect
2017-11-20	Common Stock	C	500000	$10.00	Acquired	1868966	Indirect

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-11-20	Series A-1 Convertible Preferred Stock	$	C	66667	Disposed		Common Stock (19533)	Indirect
2017-11-20	Series A-2 Convertible Preferred Stock	$	C	704846	Disposed		Common Stock (252230)	Indirect
2017-11-20	Series B Convertible Preferred Stock	$	C	736648	Disposed		Common Stock (328909)	Indirect
2017-11-20	Series C Convertible Preferred Stock	$	C	229412	Disposed		Common Stock (114320)	Indirect
2017-11-20	Series D Convertible Preferred Stock	$	C	2232014	Disposed		Common Stock (653974)	Indirect

Footnotes

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F3: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: The reported securities are held of record by OrbiMed Private Investments IV, LP ("OPI IV"). OrbiMed Capital GP IV LLC ("GP IV") is the sole general partner of OPI IV, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisers Act of 1940, as amended, is the sole managing member of GP IV. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and owner of a controlling interest in, Advisors. By virtue of such relationships, GP IV, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI IV. The Reporting Persons have designated a representative, currently Carl Gordon, a member of Advisors, to serve on the Issuer's board of directors.

F7: This report on Form 4 is jointly filed by GP IV, Advisors and Isaly. Each of the reporting persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report on Form 4 shall not be deemed an admission that any of the reporting persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.