Sec Form 4 Filing - Kehler Dean C @ NIOCORP DEVELOPMENTS LTD - 2023-03-17

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Kehler Dean C 2. Issuer Name and Ticker or Trading Symbol NIOCORP DEVELOPMENTS LTD [ NB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O NIOCORP DEVELOPMENTS LTD., 7000 YOSEMITE STREET, SUITE 115 3. Date of Earliest Transaction (MM/DD/YY) 03/17/2023 (Street) CENTENNIAL, CO80112 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Class B Common Stock of Elk Creek Resources Corp. ( 1 ) 03/17/2023 A( 2 ) 1,956,880 ( 3 ) ( 4 ) ( 4 ) Common Shares 1,956,880 ( 2 ) 1,956,880 D Class B Common Stock of Elk Creek Resources Corp. ( 1 ) 03/17/2023 A( 2 ) 555,038 ( 5 ) ( 4 ) ( 4 ) Common Shares 555,038 ( 2 ) 555,038 I By trust Warrants $ 10.284 ( 7 ) 03/17/2023 A( 2 ) 1,657,057 ( 7 ) ( 6 ) ( 6 ) Common Shares 1,853,073 ( 7 ) ( 2 ) 1,657,057 ( 7 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Kehler Dean C C/O NIOCORP DEVELOPMENTS LTD. 7000 YOSEMITE STREET, SUITE 115 CENTENNIAL, CO80112 X Signatures /s/ Neal Shah 03/21/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These shares of Class B common stock of Elk Creek Resources Corp. (f/k/a GX Acquisiton Corp. II) ("Elk Class B Shares"), an indirect subsidiary of the Issuer, are exchangeable for the Issuer's common shares on a one-for-one basis. These shares have no expiration date. ( 2 )On March 17, 2023, the Issuer consummated the business combination ("Business Combination") contemplated by the Business Combination Agreement, dated as of September 25, 2022, as amended (the "Business Combination Agreement"), entered into by and among GX Acquisiton Corp. II, the Issuer, and Big Red Merger Sub Ltd, a wholly owned subsidiary of the Issuer. After the closing of the Business Combination, GX Acquisiton Corp. II changed its name to "Elk Creek Resources Corp." GX Sponsor II LLC ("Sponsor") acquired Issuer securities and derivatives thereof in the Business Combination on behalf of its members, which were then immediately distributed to Sponsor's members, including the reporting person, on a pro rata basis for no consideration. The reporting person is a managing member of Sponsor with shared voting and investment discretion with respect to securities held of record by Sponsor, and therefore, previously indirectly beneficially owned these securities through Sponsor. ( 3 )Includes 834,060 unvested Elk Class B Shares. ( 4 )Unvested Elk Class B Shars will vest if, from the closing of the Business Combination until the tenth anniversary thereof, the volume-weighted average price ("VWAP") of the Issuer's common shares exceeds certain thresholds as follows: (a) one-half will vest if the VWAP of the Issuer's common shares exceeds $12.50 for any 20 trading days within any 30 trading day period, and (b) the remaining half will vest if the VWAP of the Issuer's common shares exceeds $15.00 for any 20 trading days within any 30 trading day period. ( 5 )Includes 236,568 unvested Elk Class B Shares. ( 6 )The warrants may be exercised commencing 30 days after the consummation of the Business Combination and expire five years after the consummation of the Business Combination or earlier upon redemption. ( 7 )Each warrant is exercisable for 1.118292212 common shares of the Issuer, such that an aggregate of 1,657,057 warrants are exercisable for an aggregate of 1,853,073 common shares, with an aggregate exercise price of $19,056,155.50 (or approximately $10.284 per share).

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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