Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^*

G1 EXECUTION SERVICES, LLC

2. Date of Event Requiring Statement (MM/DD/YYYY) 1/27/2020

3. Issuer Name and Ticker or Trading Symbol

ACHILLION PHARMACEUTICALS INC [ACHN]

(Last) (First) (Middle)

175 W. JACKSON BLVD., SUITE 1700, 501 PLAZA 2

4. Relationship of Reporting Person(s) to Issuer (Check all applicable)

_____ Director ___X___ 10% Owner
_____ Officer (give title below) _____ Other (specify below)

(Street)

CHICAGO, IL 60604

(City) (State) (Zip)

5. If Amendment, Date Original Filed(MM/DD/YYYY)

6. Individual or Joint/Group Filing(Check Applicable Line)

___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	10917	D ⁽¹⁾⁽³⁾
Common Stock	14115498	D ⁽²⁾⁽³⁾

*Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)*
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivate Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security		6. Nature of Indirect Beneficial Ownership (Instr. 5)
Call Option (right to buy)	⁽⁴⁾	12/18/2020	Common Stock	454900	$7.00	D ⁽²⁾⁽³⁾
Total Return Swap ⁽⁵⁾	⁽⁶⁾	7/29/2020	Common Stock	8000	⁽⁵⁾	D ⁽³⁾
Total Return Swap ⁽⁵⁾	⁽⁶⁾	7/30/2020	Common Stock	8000	⁽⁵⁾	D ⁽³⁾
Total Return Swap ⁽⁵⁾	⁽⁶⁾	7/31/2020	Common Stock	8000	⁽⁵⁾	D ⁽³⁾
Total Return Swap ⁽⁵⁾	⁽⁶⁾	8/3/2020	Common Stock	7100	⁽⁵⁾	D ⁽³⁾

Explanation of Responses:
(1)	These securities are directly owned by G1 Execution Services, LLC ("G1X").
(2)	These securities are directly owned by Susquehanna Securities, LLC ("SS").
(3)	G1X, Susquehanna Fundamental Investments, LLC ("SFNDI") and SS are affiliated entities under common ownership. G1X, SFNDI and SS each disclaim beneficial ownership of the reported securities except to the extent of their respective pecuniary interest therein, and this report shall not be deemed an admission that any of them are the beneficial owners of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.
(4)	These options are exercisable at any time prior to their expiration.
(5)	SFNDI has entered into cash-settled total return swaps with an unaffiliated third party financial institution, under which SFNDI acquired an aggregate of 31,100 "notional" shares of Achillion Pharmaceuticals, Inc. ("Achillion") common stock at prices ranging from $2.12 to $2.24 per share. The swap agreements provide that, upon settlement of the swaps, SFNDI will pay the applicable purchase price to the counterparty, and the counterparty will pay to SFNDI an amount equal to the then market price of the applicable number of shares of Achillion common stock. These swaps provide SFNDI with economic results that are comparable to the economic results of ownership of, but do not provide SFNDI with the power to vote or direct the voting of, or dispose of or direct the disposition of, the shares of common stock that are the subject of such swap.
(6)	Each of these total return swaps may be settled at any time prior to its expiration in SFNDI's discretion.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
G1 EXECUTION SERVICES, LLC 175 W. JACKSON BLVD., SUITE 1700 501 PLAZA 2 CHICAGO, IL 60604		X
SUSQUEHANNA FUNDAMENTAL INVESTMENTS, LLC 401 CITY AVENUE, SUITE 220 BALA CYNWYD, PA 19004		X
SUSQUEHANNA SECURITIES, LLC 401 CITY AVENUE, SUITE 220 BALA CYNWYD, PA 19004		X

Signatures
G1 Execution Services, LLC By: /s/ Brian Sopinsky Name: Brian Sopinsky Title: Secretary		1/30/2020
^**Signature of Reporting Person		Date
Susquehanna Fundamental Investments, LLC By: /s/ Brian Sopinsky Name: Brian Sopinsky Title: Assistant Secretary		1/30/2020
^**Signature of Reporting Person		Date
Susquehanna Securities, LLC By: /s/ Brian Sopinsky Name: Brian Sopinsky Title: Secretary		1/30/2020
^**Signature of Reporting Person		Date