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: Polaris Venture Management Co. V, L.L.C. (10% Owner)
Reporting Person: Polaris Venture Partners V, L.P. (10% Owner)
Reporting Person: Polaris Venture Partners Entrepreneurs' Fund V, L.P. (10% Owner)
Reporting Person: Polaris Venture Partners Founders' Fund V, L.P. (10% Owner)
Reporting Person: Polaris Venture Partners Special Founders' Fund V, L.P. (10% Owner)
Reporting Person: Flint Jonathan A (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-11-20	Common Stock	C	18848	—	Acquired	18848	Indirect
2017-11-20	Common Stock	C	367	—	Acquired	367	Indirect
2017-11-20	Common Stock	C	129	—	Acquired	129	Indirect
2017-11-20	Common Stock	C	188	—	Acquired	188	Indirect
2017-11-20	Common Stock	C	243385	—	Acquired	262233	Indirect
2017-11-20	Common Stock	C	4743	—	Acquired	5110	Indirect
2017-11-20	Common Stock	C	1667	—	Acquired	1796	Indirect
2017-11-20	Common Stock	C	2433	—	Acquired	2621	Indirect
2017-11-20	Common Stock	C	317376	—	Acquired	579609	Indirect
2017-11-20	Common Stock	C	6185	—	Acquired	11295	Indirect
2017-11-20	Common Stock	C	2173	—	Acquired	3969	Indirect
2017-11-20	Common Stock	C	3173	—	Acquired	5794	Indirect
2017-11-20	Common Stock	C	110312	—	Acquired	689921	Indirect
2017-11-20	Common Stock	C	2150	—	Acquired	13445	Indirect
2017-11-20	Common Stock	C	755	—	Acquired	4724	Indirect
2017-11-20	Common Stock	C	1102	—	Acquired	6896	Indirect
2017-11-20	Common Stock	C	631041	—	Acquired	1320962	Indirect
2017-11-20	Common Stock	C	12298	—	Acquired	25743	Indirect
2017-11-20	Common Stock	C	4322	—	Acquired	9046	Indirect
2017-11-20	Common Stock	C	6310	—	Acquired	13206	Indirect
2017-11-20	Common Stock	P	482467	$10.00	Acquired	1803429	Indirect
2017-11-20	Common Stock	P	9403	$10.00	Acquired	35146	Indirect
2017-11-20	Common Stock	P	3305	$10.00	Acquired	12351	Indirect
2017-11-20	Common Stock	P	4825	$10.00	Acquired	18031	Indirect

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-11-20	Series A-1 Convertible Preferred Stock	$	C	64329	Disposed		Common Stock (18848)	Indirect
2017-11-20	Series A-1 Convertible Preferred Stock	$	C	1254	Disposed		Common Stock (367)	Indirect
2017-11-20	Series A-1 Convertible Preferred Stock	$	C	441	Disposed		Common Stock (129)	Indirect
2017-11-20	Series A-1 Convertible Preferred Stock	$	C	643	Disposed		Common Stock (188)	Indirect
2017-11-20	Series A-2 Convertible Preferred Stock	$	C	680130	Disposed		Common Stock (243385)	Indirect
2017-11-20	Series A-2 Convertible Preferred Stock	$	C	13256	Disposed		Common Stock (4743)	Indirect
2017-11-20	Series A-2 Convertible Preferred Stock	$	C	4659	Disposed		Common Stock (1667)	Indirect
2017-11-20	Series A-2 Convertible Preferred Stock	$	C	6801	Disposed		Common Stock (2433)	Indirect
2017-11-20	Series B Convertible Preferred Stock	$	C	710817	Disposed		Common Stock (317376)	Indirect
2017-11-20	Series B Convertible Preferred Stock	$	C	13854	Disposed		Common Stock (6185)	Indirect
2017-11-20	Series B Convertible Preferred Stock	$	C	4869	Disposed		Common Stock (2173)	Indirect
2017-11-20	Series B Convertible Preferred Stock	$	C	7108	Disposed		Common Stock (3173)	Indirect
2017-11-20	Series C Convertible Preferred Stock	$	C	221638	Disposed		Common Stock (110312)	Indirect
2017-11-20	Series C Convertible Preferred Stock	$	C	4315	Disposed		Common Stock (2150)	Indirect
2017-11-20	Series C Convertible Preferred Stock	$	C	1516	Disposed		Common Stock (755)	Indirect
2017-11-20	Series C Convertible Preferred Stock	$	C	2213	Disposed		Common Stock (1102)	Indirect
2017-11-20	Series D Convertible Preferred Stock	$	C	2153746	Disposed		Common Stock (631041)	Indirect
2017-11-20	Series D Convertible Preferred Stock	$	C	41976	Disposed		Common Stock (12298)	Indirect
2017-11-20	Series D Convertible Preferred Stock	$	C	14752	Disposed		Common Stock (4322)	Indirect
2017-11-20	Series D Convertible Preferred Stock	$	C	21537	Disposed		Common Stock (6310)	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: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

F7: 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.

F8: 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.

F9: 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.

F10: 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.