NB · Niocorp Developments Ltd · Insider Trading

34% of the options vested on the grant date, 33% of the options will vest on the first anniversary of the grant date, and the remaining balance will vest on the second anniversary of the grant date (July 6, 2028).

34% of the options vested on the grant date, 33% of the options will vest on the first anniversary of the grant date, and the remaining balance will vest on the second anniversary of the grant date (July 6, 2028).

34% of the options vested on the grant date, 33% of the options will vest on the first anniversary of the grant date, and the remaining balance will vest on the second anniversary of the grant date (July 6, 2028).

34% of the options vested on the grant date, 33% of the options will vest on the first anniversary of the grant date, and the remaining balance will vest on the second anniversary of the grant date (July 6, 2028).

34% of the options vested on the grant date, 33% of the options will vest on the first anniversary of the grant date, and the remaining balance will vest on the second anniversary of the grant date (July 6, 2028).

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

34% of the options vested on the grant date and the remainder will vest in equal installments on each anniversary of the grant date until August 18, 2027.

Reflects exchange of Class B common stock of Elk Creek Resources Corp ("Elk Class B Shares") exchanged for the Issuer's common shares on a one-for-one basis. Unvested Elk Class B Shares 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.

Elk Class B shares were acquired from GX Sponsor II LLC ("Sponsor") in a pro rata distribution to all Sponsor members immediately following the closing of the business combination (the "Business Combination") contemplated by the Business Combination Agreement, dated as of September 25, 2022, as amended, entered into by and among GX Acquisition 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 Acquisition Corp. II became an indirect subsidiary of the Issuer and changed its name to "Elk Creek Resources Corp." Reflects vested Elk Class B shares eligible for exchange to Issuer's common shares.

Reflects exchange of Class B common stock of Elk Creek Resources Corp ("Elk Class B Shares") exchanged for the Issuer's common shares on a one-for-one basis. Unvested Elk Class B Shares 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.

Includes 239,996 unvested Elk Class B Shares.

Exercisable immediately on the issue date.

Exercisable immediately on the issue date.

On November 13, 2023, the reporting person purchased 183,422 units (each, a "Unit") from NioCorp Developments Ltd. (the "Issuer") in a private placement. Each Unit consists of one common share, without par value (a "Common Share"), of the Issuer, one warrant to purchase one Common Share (a "Series A Warrant") and one-half of one warrant to purchase one Common Share (together with the series A Warrants, the "Warrants"). The price per Unit was $1.7675, which amount includes $0.125 per Warrant underlying each Unit.

Exercisable beginning six months and one day from the issue date on May 14, 2025.

On November 13, 2023, the reporting person purchased 56,577 units (each, a "Unit") from NioCorp Developments Ltd. (the "Issuer") in a private placement. Each Unit consists of one common share, without par value (a "Common Share"), of the Issuer, one warrant to purchase one Common Share (a "Series A Warrant") and one-half of one warrant to purchase one Common Share (together with the Series A Warrants, the "Warrants"). The price per Unit was $1.7675, which amount includes $0.125 per Warrant underlying each Unit.

Exercisable beginning six months and one day from the issue date on May 14, 2025.

On November 13, 2023, the reporting person purchased 56,577 units (each, a "Unit") from NioCorp Developments Ltd. (the "Issuer") in a private placement. Each Unit consists of one common share, without par value (a "Common Share"), of the Issuer, one warrant to purchase one Common Share (a "Series A Warrant") and one-half of one warrant to purchase one Common Share (together with the Series A Warrants, the "Warrants"). The price per Unit was $1.7675, which amount includes $0.125 per Warrant underlying each Unit.

Exercisable immediately on the issue date.

On November 13, 2023, the reporting person purchased 183,422 units (each, a "Unit") from NioCorp Developments Ltd. (the "Issuer") in a private placement. Each Unit consists of one common share, without par value (a "Common Share"), of the Issuer, one warrant to purchase one Common Share (a "Series A Warrant") and one-half of one warrant to purchase one Common Share (together with the series A Warrants, the "Warrants"). The price per Unit was $1.7675, which amount includes $0.125 per Warrant underlying each Unit.

Exercisable immediately on the issue date.