OmniAb SPAC Presentation Deck

TRANSACTION SUMMARY (1) (2) I ■ ■ Transaction Summary OmniAb, Inc., an antibody discovery business wholly owned by Ligand, has entered into a definitive agreement to merge with Avista Public Acquisition Corp. II (APAC) (NASDAQ: AHPA), valuing OmniAb at a fully diluted pre- money equity valuation of $850 million OmniAb to become an independent publicly traded company Anchored spin-off transaction is backed with committed capital from Avista and Ligand Tax-free distribution for existing Ligand shareholders via all SPAC consideration All-primary transaction will result in gross proceeds of up to $266 million, through a combination of: APAC's $236 million cash in trust Avista to invest $15 million at $10.00 per share and provide up to an additional $100 million to backstop redemptions $15 million contribution from Ligand Earn-out payable to existing Ligand shareholders of 7.5mm shares @ $12.50 and 7.5mm shares @$15.00 33% of Avista's sponsor shares (1.9 million) subject to earnout at the same thresholds as Ligand shareholders Closing Expected 2H 2022 ($m) Sources Note: APAC Cash Avista Minimum Commitment Ligand Contribution Total Illustrative Sources & Uses $236 15 15 $266 Uses Cash to Balance Sheet Estimated Transaction Fees Total $250 16 (1) $266 ($m, except per share amount) Pro Forma Enterprise Value Share Price Pro Forma Shares Outstanding Post-Transaction Equity Value (-Cash) Pro Forma Enterprise Value Assumes no redemptions. Excludes impact of 8.2 million Avista warrants and 7.7 million public warrants, each struck at $11.50. Excludes impact of 15.0 million Ligand earnout shares and 1.9 million Avista earnout shares. Up to 37.5% of Avista's earnout shares are immediately vested pro rata to any utilization of the $100 million backstop facility. Excludes OmniAb's expenses. Includes 1.5 million co-investment shares and 3.8 million sponsor shares. Ligand Shareholders Illustrative Pro Forma Ownership APAC Shareholders Avista Shares 20.3% 4.7%(²) 75.0% 6 $10.00 113.3 $1,133 (250) $884 OmniAb

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