Description of Business, Contribution and Exchange, and Liquidity	6 Months Ended
Jun. 30, 2021
Accounting Policies [Abstract]
Description of Business, Contribution and Exchange, and Liquidity	1. Description of business, contribution and exchange, and liquidity Business Monte Rosa Therapeutics, Inc. is a biotechnology company developing a portfolio of novel small molecule precision medicines that employ the body’s natural mechanisms to selectively degrade therapeutically-relevant proteins. As used in these condensed combined and consolidated financial statements, unless the context otherwise requires, references to the Company or Monte Rosa refer to Monte Rosa Therapeutics, Inc. and its wholly owned subsidiaries Monte Rosa Therapeutics AG and Monte Rosa Therapeutics Securities Corp. The Company was incorporated in Delaware in November 2019 and is headquartered in Boston, Massachusetts with research operations in both Boston and Basel, Switzerland. Contribution and exchange Monte Rosa Therapeutics AG, a Swiss operating company, was incorporated in April 2018. Monte Rosa Therapeutics, Inc. was incorporated in November 2019. In 2020, Monte Rosa Therapeutics, Inc. and Monte Rosa Therapeutics AG, entities under common control since the incorporation of Monte Rosa Therapeutics, Inc., consummated a contribution and exchange agreement, or the Contribution and Exchange, whereby Monte Rosa Therapeutics, Inc. acquired the net assets and shareholdings of Monte Rosa Therapeutics AG via a one-for-one exchange of equity between Monte Rosa Therapeutics, Inc. and the shareholders of Monte Rosa Therapeutics AG in a common control reorganization. Accordingly, the historical financial information has been retrospectively adjusted to include the historical results and financial position of Monte Rosa Therapeutics, Inc. combined with Monte Rosa Therapeutics AG’s historical results and financial position, after the elimination of all intercompany accounts and transactions. Initial Public Offering In June 2021 the Company completed its initial public offering, or IPO, and issued an aggregate of 11,700,000 shares of common stock at a price to the public of $19.00 per share. The Company received aggregate net proceeds from the IPO of $203.9 million, after deducting underwriting discounts and commissions of $15.6 million and offering costs of $2.9 million. In connection with the IPO, the Company granted the underwriters a 30-day option to purchase an additional 1,755,000 shares. In July 2021, the underwriters exercised the option in full and the Company issued 1,755,000 shares of common stock for aggregate net proceeds of $31.0 million after deducting underwriter discounts and commissions of $2.3 million. Immediately prior to consummation of the IPO, all outstanding shares of the Company's Series A, Series A-2, Series B and Series C convertible preferred stock were converted into 31,068,102 shares of common stock. The Company's common stock began trading on the Nasdaq Global Select Market on June 24, 2021 under the symbol “GLUE”. Liquidity considerations Since inception, the Company has devoted substantially all its efforts to business planning, research and development, recruiting management and technical staff, and raising capital and has financed its operations primarily through the issuance of convertible preferred shares. The Company’s continued discovery and development of its product candidates will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. As of June 30, 2021, the Company had an accumulated deficit of $78.8 million. The Company has incurred losses and negative cash flows from operations since inception, including net losses of $30.7 million and $9.7 million for the six months ended June 30, 2021 and 2020, respectively. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future as the Company continues to develop its product candidates. The Company currently expects that its cash and cash equivalents of $357.1 million as of June 30, 2021 will be sufficient to fund operating expenses and capital requirements for at least 12 months from the date the condensed combined and consolidated financial statements are issued. However, additional funding will be necessary to fund future discovery research, pre-clinical and clinical activities. The Company will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and licensing arrangements. Although it has been successful in raising capital in the past, there is no assurance that the Company will be successful in obtaining such additional financing on terms acceptable to it, if at all, and the Company may not be able to enter into collaborations or other arrangements. If the Company is unable to obtain funding, it could be forced to delay, reduce or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect the Company’s business prospects, even the ability to continue operations. Coronavirus pandemic The coronavirus, or COVID-19, pandemic has spread worldwide, and has caused many governments to implement measures to slow the spread of the outbreak through quarantines, travel restrictions, heightened border scrutiny and other measures. The outbreak and government measures taken in response have also had a significant impact, both directly and indirectly, on businesses and commerce, as worker shortages have occurred; supply chains have been disrupted; facilities and production have been suspended; and demand for certain goods and services, such as medical services and supplies, has spiked, while demand for other goods and services, such as travel, has fallen. The future progression of the outbreak and its effects on the Company’s business and operations are uncertain. To date, our operations have not been significantly impacted by the COVID-19 pandemic. The actual and perceived impact of the COVID-19 pandemic is changing daily, and its ultimate effect on the Company cannot be predicted. As a result, there can be no assurance that the Company will not experience additional negative impacts associated with COVID-19, which could be significant. The COVID-19 pandemic may negatively impact the Company’s business, financial condition and results of operations causing interruptions or delays in the Company’s programs and services.

Description of Business, Contribution and Exchange, and Liquidity

6 Months Ended

Jun. 30, 2021

Description of Business, Contribution and Exchange, and Liquidity

1. Description of business, contribution and exchange, and liquidity

Business

Monte Rosa Therapeutics, Inc. is a biotechnology company developing a portfolio of novel small molecule precision medicines that employ the body’s natural mechanisms to selectively degrade therapeutically-relevant proteins. As used in these condensed combined and consolidated financial statements, unless the context otherwise requires, references to the Company or Monte Rosa refer to Monte Rosa Therapeutics, Inc. and its wholly owned subsidiaries Monte Rosa Therapeutics AG and Monte Rosa Therapeutics Securities Corp. The Company was incorporated in Delaware in November 2019 and is headquartered in Boston, Massachusetts with research operations in both Boston and Basel, Switzerland.

Contribution and exchange

Monte Rosa Therapeutics AG, a Swiss operating company, was incorporated in April 2018. Monte Rosa Therapeutics, Inc. was incorporated in November 2019. In 2020, Monte Rosa Therapeutics, Inc. and Monte Rosa Therapeutics AG, entities under common control since the incorporation of Monte Rosa Therapeutics, Inc., consummated a contribution and exchange agreement, or the Contribution and Exchange, whereby Monte Rosa Therapeutics, Inc. acquired the net assets and shareholdings of Monte Rosa Therapeutics AG via a one-for-one exchange of equity between Monte Rosa Therapeutics, Inc. and the shareholders of Monte Rosa Therapeutics AG in a common control reorganization. Accordingly, the historical financial information has been retrospectively adjusted to include the historical results and financial position of Monte Rosa Therapeutics, Inc. combined with Monte Rosa Therapeutics AG’s historical results and financial position, after the elimination of all intercompany accounts and transactions.

Initial Public Offering

In June 2021 the Company completed its initial public offering, or IPO, and issued an aggregate of 11,700,000 shares of common stock at a price to the public of $19.00 per share. The Company received aggregate net proceeds from the IPO of $203.9 million, after deducting underwriting discounts and commissions of $15.6 million and offering costs of $2.9 million. In connection with the IPO, the Company granted the underwriters a 30-day option to purchase an additional 1,755,000 shares. In July 2021, the underwriters exercised the option in full and the Company issued 1,755,000 shares of common stock for aggregate net proceeds of $31.0 million after deducting underwriter discounts and commissions of $2.3 million.

Immediately prior to consummation of the IPO, all outstanding shares of the Company's Series A, Series A-2, Series B and Series C convertible preferred stock were converted into 31,068,102 shares of common stock. The Company's common stock began trading on the Nasdaq Global Select Market on June 24, 2021 under the symbol “GLUE”.

Liquidity considerations

Since inception, the Company has devoted substantially all its efforts to business planning, research and development, recruiting management and technical staff, and raising capital and has financed its operations primarily through the issuance of convertible preferred shares.

The Company’s continued discovery and development of its product candidates will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

As of June 30, 2021, the Company had an accumulated deficit of $78.8 million. The Company has incurred losses and negative cash flows from operations since inception, including net losses of $30.7 million and $9.7 million for the six months ended June 30, 2021 and 2020, respectively. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future as the Company continues to develop its product candidates. The Company currently expects that its cash and cash equivalents of $357.1 million as of June 30, 2021 will be sufficient to fund operating expenses and capital requirements for at least 12 months from the date the condensed combined and consolidated financial statements are issued. However, additional funding will be necessary to fund future discovery

research, pre-clinical and clinical activities. The Company will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and licensing arrangements. Although it has been successful in raising capital in the past, there is no assurance that the Company will be successful in obtaining such additional financing on terms acceptable to it, if at all, and the Company may not be able to enter into collaborations or other arrangements. If the Company is unable to obtain funding, it could be forced to delay, reduce or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect the Company’s business prospects, even the ability to continue operations.

Coronavirus pandemic

The coronavirus, or COVID-19, pandemic has spread worldwide, and has caused many governments to implement measures to slow the spread of the outbreak through quarantines, travel restrictions, heightened border scrutiny and other measures. The outbreak and government measures taken in response have also had a significant impact, both directly and indirectly, on businesses and commerce, as worker shortages have occurred; supply chains have been disrupted; facilities and production have been suspended; and demand for certain goods and services, such as medical services and supplies, has spiked, while demand for other goods and services, such as travel, has fallen. The future progression of the outbreak and its effects on the Company’s business and operations are uncertain. To date, our operations have not been significantly impacted by the COVID-19 pandemic.

The actual and perceived impact of the COVID-19 pandemic is changing daily, and its ultimate effect on the Company cannot be predicted. As a result, there can be no assurance that the Company will not experience additional negative impacts associated with COVID-19, which could be significant. The COVID-19 pandemic may negatively impact the Company’s business, financial condition and results of operations causing interruptions or delays in the Company’s programs and services.