Table of Contents Stock-based compensation expense is based on the grant date fair value of the applicable equity grant. For restricted stock unit awards, the fair value was equivalent to the closing market price of Howmet’s common stock on the date of grant. The weighted average grant date fair value of the 2020 performance stock awards with a market condition scaled by a TSR multiplier was $21.33, and the weighted average grant date fair value of the April 2020 senior executive performance stock awards with a market condition (achievement of certain stock price thresholds) was $2.57. The weighted average grant date fair value of the 2019 performance stock awards with a market condition (achievement of certain stock price thresholds) was $11.93. The grant date fair value of the 2018 performance stock awards containing a market condition (scaled by TSR multiplier) was $20.25. The 2020, 2019 and 2018 performance awards were valued using a Monte Carlo model. A Monte Carlo simulation uses assumptions of stock price behavior to estimate the probability of satisfying market conditions and the resulting fair value of the award. The risk-free interest rate (0.3% in 2020, 1.6% in 2019 and in 2.7% 2018) was based on a yield curve of interest rates at the time of the grant based on the remaining performance period. In 2020 volatility was estimated using a blended rate of Howmet's historical volatility and a peer-based volatility (48.3%) due to the Arconic Inc. Separation Transaction and the related changes in the nature of the business. In 2019 volatility was estimated using implied and historical volatility (33.4%). Because of limited historical information due to the Alcoa Inc. Separation Transaction, 2018 volatility (32.0%) was estimated using implied volatility, and the representative price return approach, which uses price returns of comparable companies, was used to develop a correlation assumption. For stock options, the fair value was estimated on the date of grant using a lattice-pricing model, which generated a result of $9.79 per option in 2018. There were no stock options issued in 2020 or 2019. The lattice-pricing model uses a number of assumptions to estimate the fair value of a stock option, including a risk-free interest rate, dividend yield, volatility, exercise behavior, and contractual life. The following paragraph describes in detail the assumptions used to estimate the fair value of stock options granted in 2018. The risk-free interest rate (2.5%) was based on a yield curve of interest rates at the time of the grant based on the contractual life of the option. The dividend yield (0.9%) was based on a one-year average. Volatility (34.0%) was based on comparable companies and implied volatilities over the term of the option. Howmet utilized historical option forfeiture data to estimate annual post-vesting forfeitures (6%). Exercise behavior (61%) was based on a weighted average exercise ratio (exercise patterns for grants issued over the number of years in the contractual option term) of an option’s intrinsic value resulting from historical employee exercise behavior. Based upon the other assumptions used in the determination of the fair value, the life of an option (6.0) was an output of the lattice-pricing mod. The activity for stock options and stock awards during 2020 was as follows (options and awards in millions): As a result of the Arconic Inc. Separation Transaction, all stock options and stock awards relating to Arconic Corporation employees were cancelled. (1) As a result of the Arconic Inc. Separation Transaction, all stock options and stock awards relating to Howmet employees were adjusted to reflect the Arconic Inc. Separation Transaction. (2) As of December 31, 2020, the number of stock options outstanding had a weighted average remaining contractual life of 2.9 years and a total intrinsic value of $18. Additionally, 3.1 million of the stock options outstanding were fully vested and exercisable and had a weighted average remaining contractual life of 2.8 years, a weighted average exercise price of $24.32, and a total intrinsic value of $18 as of December 31, 2020. In 2020, 2019, and 2018, the cash received from stock option exercises was $33, $56, and $16 and the total tax benefit realized from these exercises was $3, $4, and $2, respectively. The total intrinsic value of stock options exercised during 2020, 2019, and 2018 was $14, $17, and $7, respectively. 84 Stock options Stock awards Number of options Weighted average exercise price Number of awards Weighted average FMV per award Outstanding, December 31, 2019 7  $ 25.75  7  $ 22.05  Granted —  —  6  10.89  Exercised (2) 21.65  —  —  Converted —  —  (4) 19.54  Expired or forfeited (1) 30.12  —  19.57  Canceled due to Arconic Inc. Separation Transaction (1) 27.85  (1) 23.84  Adjustment due to Arconic Inc. Separation Transaction —  24.35  1  19.10  Performance share adjustment —  —  —  21.20  Outstanding, December 31, 2020 3  $ 24.47  9  $ 13.68  (1) (2)