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EQUITY - Treasury stocks (Details) - BRL (R$) R$ / shares in Units, R$ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Value of shares |  |  |
Balance at beginning of year | R$ 31,085,210 | R$ 27,173,127 | R$ 25,938,571
Exercise of stock options | 143,982 | 9,596 | 29,411
Balance at end of year | R$ 42,815,649 | R$ 31,085,210 | R$ 27,173,127
Common shares |  |  |
Number of shares |  |  |
Balance at beginning of the year | 571,929,945 | 571,929,945 | 571,929,945
Balance at end of period | 571,929,945 | 571,929,945 | 571,929,945
Preferred shares |  |  |
Number of shares |  |  |
Balance at beginning of the year | 1,129,231,487 | 1,127,010,827 | 1,124,233,755
Exercise of long-term incentive plan | 4,585,414 | 2,220,660 | 2,777,072
Balance at end of period | 1,133,816,901 | 1,129,231,487 | 1,127,010,827
Treasury Stocks |  |  |
EQUITY |  |  |
Average acquisition cost | R$ 12.43 | R$ 13.62 | R$ 12.72
Value of shares |  |  |
Balance at beginning of year | R$ (229,309) | R$ (242,542) | R$ (280,426)
Exercise of stock options | 76,900 | 13,233 | 37,884
Balance at end of year | R$ (152,409) | R$ (229,309) | R$ (242,542)
Treasury Stocks | Common shares |  |  |
Number of shares |  |  |
Balance at beginning of the year | 1,697,538 | 1,697,538 | 1,697,538
Balance at end of period | 1,697,538 | 1,697,538 | 1,697,538
Value of shares |  |  |
Balance at beginning of year | R$ 557 | R$ 557 | R$ 557
Balance at end of year | R$ 557 | R$ 557 | R$ 557
Treasury Stocks | Preferred shares |  |  |
Number of shares |  |  |
Balance at beginning of the year | 16,799,758 | 19,020,418 | 21,797,490
Exercise of long-term incentive plan | (4,585,414) | (2,220,660) | (2,777,072)
Balance at end of period | 12,214,344 | 16,799,758 | 19,020,418
Value of shares |  |  |
Balance at beginning of year | R$ 228,752 | R$ 241,985 | R$ 279,869
Exercise of stock options | (76,900) | (13,233) | (37,884)
Balance at end of year | R$ 151,852 | R$ 228,752 | R$ 241,985

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