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Shareholders' Equity (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2020
Shareholders' Equity |
Reserved Shares of Common Stock | ​
​ | ​ | ​
Options granted and outstanding |  | 11,938,528
Options available for future grant |  | 4,089,584
Common stock warrants |  | 243,115
Total shares reserved |  | 16,271,227
Schedule of Stockholders' Equity Note, Warrants or Rights | ​
​ | ​ | ​ | ​ | ​ | ​
Outstanding At |  | ​ |  | ​ | ​
December 31, 2020 | ​ | Expiration Date | ​ | Exercise Price
43,115 | ​ | May 18, 2023 | ​ | $ | 9.94
200,000 | ​ | April 12, 2023 | ​ | $ | 23.00

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- Definition Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 50 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6784392&loc=d3e188667-122775 + Details
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