Share-Based Compensation Expenses and Cash Awards
Our results of operations have been affected by, and we expect our results of operations to continue to be affected by, our share-based compensation expenses and cash awards, which consist of charges taken relating to grants of mainly RSUs as well as stock options, non-vested shares, and cash awards to employees.
Restricted Share Units (RSUs). We adopted two long-term incentive plans in October 2005 and September 2011, respectively, which permit the grant of options or RSUs to our employees and non-employees where each unit represents two ordinary shares. The actual awards will be determined by our compensation committee. The 2005 plan was terminated in October 2010. We recognized share-based compensation expenses regarding RSUs under the long-term incentive plan totaling $0.1 million, $4.8 million and $23.8 million in 2019, 2020 and 2021, respectively. Of the total share-based compensation expenses recognized, nil, $4.8 million and $23.2 million in 2019, 2020 and 2021, respectively, were settled in cash. We measure and recognize compensation expense for all share-based payments at fair value.
Set forth below is a summary of our historical share-based compensation plans for the years ended December 31, 2019, 2020 and 2021 as reflected in our consolidated financial statements. However, we did not grant RSUs in 2019 but granted stock options to employees instead.
We made grants of 1,208,785 RSUs to our employees on September 28, 2016. The vesting schedule for such RSU grants is as follows: 91.93% of the RSU grants vested immediately and were settled by cash in the amount of $9.2 million on the grant date, with the remainder vesting equally on each of September 30, 2017, 2018 and 2019, which will be settled by our ordinary shares, subject to certain forfeiture events.
We made grants of 580,235 RSUs to our employees on September 29, 2017. The vesting schedule for such RSU grants is as follows: 96.91% of the RSU grants vested immediately and were settled by cash in the amount of $6.1 million on the grant date, with the remainder vesting equally on each of September 30, 2018, 2019 and 2020, which will be settled by our ordinary shares, subject to certain forfeiture events.
We made grants of 676,273 RSUs to our employees on September 26, 2018. The vesting schedule for such RSU grants is as follows: 97.15% of the RSU grants vested immediately and were settled by cash in the amount of $3.8 million on the grant date, with the remainder vesting equally on each of September 30, 2019, 2020 and 2021, which will be settled by our ordinary shares, subject to certain forfeiture events.
We made grants of 1,402,714 RSUs to our employees on September 28, 2020. The vesting schedule for such RSU grants is as follows: 98.68% of the RSU grants vested immediately and were settled by cash in the amount of $4.8 million on the grant date, with the remainder vesting equally on each of September 30, 2021, 2022 and 2023, which will be settled by our ordinary shares, subject to certain forfeiture events.
We made grants of 2,604,545 RSUs to our employees on September 28, 2021. The vesting schedule for such RSU grants is as follows: 85.63% of the RSU grants vested immediately and were settled by cash in the amount of $23.2 million on the grant date, with the remainder vesting equally on each of September 30, 2022, 2023 and 2024, which will be settled by our ordinary shares, subject to certain forfeiture events.
The amount of share-based compensation expense with regard to the RSUs granted to our employees on September 28, 2016, September 29, 2017, September 26, 2018, September 28, 2020 and September 28, 2021 was $8.30 per ADS, $10.93 per ADS, $5.76 per ADS, $3.44 per ADS and $10.39 per ADS, respectively, which was based on the trading price of our ADSs on that day.
Employee stock options. We made grants of 2,226,690 units of stock option to purchase 2,226,690 units ADS to certain employees at an exercise price of $2.27 on September 30, 2019. The vesting schedule was that 50% of the options vest half year after the date of grant and 50% of the options vest one year after the date of grant. During 2020, 114,500 units, 39,000 units and 10,000 units of stock option to purchase 114,500 units, 39,000 units and 10,000 units ADS were grant to certain employees at an exercise price of $2.74, $3.9 and $3.35 on March 31, 2020, August 11, 2020 and September 25, 2020, respectively. The options granted in 2020 were fully vested on October 1, 2020. We recognized share-based compensation expenses regarding stock options under the long-term incentive plan totaling $0.3 million and $0.7 million in 2019 and 2020, respectively.