I-Mab Added to FTSE Russell Global Equity Index Series

SHANGHAI and GAITHERSBURG,Md.,Sept. 2,2021 --I-Mab (the "Company") (Nasdaq: IMAB),a clinical stage biopharmaceutical company committed to the discovery,development and commercialization of novel biologics,today announced that I-Mab will be added tothe followingFTSE Global Equity Index Series ("GEIS"),following FTSE's most recent semi-annual review. These inclusions will become effective after the market close on Friday,September 17,2021:

FTSE Global Mid Cap Index

FTSE All-World Index

FTSE Global All Cap Index

FTSE Global Total Cap Index

FTSE Russell is a global index leader that provides innovative benchmarking,analytics and data solutions for investors worldwide. FTSE Russell calculates thousands of indexes that measure and benchmark markets and asset classes in more than 70 countries,covering 98% of the investable market globally. FTSE Russell index expertise and products are used extensively by institutional and retail investors globally. FTSE GEIS provides a robust global equity index framework. The series includes over 16,000 large,mid,small,and micro cap securities across 49 developed and emerging markets globally,with a wide range of modular indexes available to target specific markets and market segments. For more information,please refer to the Index page on FTSE's website at https://www.ftserussell.com/products/indices/geisac.

"The FTSE indices are one of the most visible and well-tracked index families in the world. Being included in this marquee equity index series is a tremendous honor and validation of the inspiring journey I-Mab has travelled since its IPO in January 2020," commented Mr. Jielun Zhu,Director and Chief Financial Officer of I-Mab. "This significant capital market milestone marks the third flagship equity index series I-Mab has been added to,following its inclusion in the NASDAQ Biotech Index in December 2020 and the MSCI China All Shares Index in May 2021. Our recent interim corporate updates have demonstrated that we are not only making rapid progress advancing our deep and highly innovative pipeline globally,but are also well on our way to grow into a fully integrated biopharma company in the next few years. We are extremely excited to share the fruits of our future success with our shareholders."

About I-Mab

I-Mab (Nasdaq: IMAB) is an innovation-driven global biotech company focusing on discovery,development and soon commercialization of novel and highly differentiated biologics in immuno-oncology therapeutic area. The Company's mission is to bring transformational medicines to patients around the world through drug innovation. I-Mab's globally competitive pipeline of more than 15 clinical and pre-clinical stage drug candidates is driven by its internal R&D capability and global licensing partnerships,based on the Company's unique Fast-to-Proof-of-Concept and Fast-to-Market pipeline development strategies. The Company is now rapidly progressing from a clinical stage biotech company to a fully integrated global biopharmaceutical company with cutting-edge global R&D capabilities,a world-class GMP manufacturing facility and commercialization capability. I-Mab has established its global footprint in Shanghai (headquarters),Beijing,Hangzhou,Guangzhou,Lishui and Hong Kong in China,and Maryland and San Diego in the United States. For more information,please visit http://ir.i-mabbiopharma.comand follow I-Mab on LinkedIn,Twitterand WeChat.

Forward Looking Statements

This press release includes certain disclosures which contain "forward-looking statements." You can identify forward-looking statements because they contain words such as "anticipate" and "expected." Forward-looking statements are based on I-Mab's current expectations and assumptions. Because forward-looking statements relate to the future,they are subject to inherent uncertainties,risks and changes in circumstances that may differ materially from those contemplated by the forward-looking statements,which are neither statements of historical fact nor guarantees or assurances of future performance. Important factors that could cause actual results to differ materially from those in the forward-looking statements are set forth in filings with the U.S. Securities and Exchange Commission. I-Mab undertakes no obligation to publicly update or revise any forward-looking statements,whether as a result of new information,future events or otherwise,except as may be required by law.

I-Mab Contacts

Jielun Zhu

Chief Financial Officer

jielun.zhu@i-mabbiopharma.com

+86 21 6057 8000

Gigi Feng

Chief Communications Officer

gigi.feng@i-mabbiopharma.com

+86 21 6057 5709

Investor Inquiries

The Piacente Group,Inc.

Emilie Wu

E-mail: emilie@thepiacentergroup.com

Office line: +86 21 6039 8363

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