| Explanation of Responses: |
| (1) | The reported sales were to cover taxes upon the vesting of restricted stock units. |
| (2) | The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 5, 2020. |
| (3) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.08 to $108.97 inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (4) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $109.09 to $109.65, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (5) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $110.13 to $111.08 inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (6) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.53 to $111.80 inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (7) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.80 to $112.78, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (8) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $112.95 to $113.86 inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (9) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $113.96 to $114.84, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (10) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $115.00 to $115.99, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (11) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $116.01 to $116.96 inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (12) | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $117.14 to $117.99, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. |
| (13) | The option vests in 48 equal monthly installments beginning on the one month anniversary of February 23, 2017. |
| (14) | The option vests in 48 equal monthly installments beginning on the one month anniversary of February 26, 2018. |
| (15) | The option vests in 48 equal monthly installments beginning on the one month anniversary of February 22, 2019. |
| (16) | The option vests in 48 equal monthly installments beginning on the one month anniversary of February 24, 2020. |