Christophe Arbet-Engels

Insider

First SEC filing: Oct. 3, 2025 · Latest: Oct. 3, 2025

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Insider at

0 buys (P) 0 sells (S) Net: $0 + 4 non-open-market transactions below last 12 months, based on the transactions shown below

Price change vs current quote, split-adjusted for corporate actions since the filing — not benchmarked, not annualized, not size-weighted

No open-market trades on record; showing all filings.

Date	Ticker	Code	Shares	Price	Value	Owned after	Δ own	A/D	vs now
Oct. 1, 2025	ALT	A	150,000	—	—	150,000 Direct	—	Acquired	(price as of 2026-08-21)
Oct. 1, 2025	ALT	A	450,000	—	—	450,000 Direct	—	Acquired	(price as of 2026-08-21)
May 25, 2020	TPST	A	80,000	—	—	80,000 Direct	—	Acquired	(price as of 2026-08-21)
Feb. 10, 2020	TPST	A	140,000	—	—	140,000 Direct	—	Acquired	(price as of 2026-08-21)

P = Open-market purchase · S = Sale · A = Grant/award · M = Option exercise · G = Gift · F = Tax withholding

Insider transactions are not a recommendation; sales are often driven by liquidity or tax reasons.

Options, RSUs and convertible securities reported on Form 4 Table II.

Date	Ticker	Security	Underlying	Exercise price	Expiration	Shares	A/D
Oct. 1, 2025	ALT	Restricted Stock Units	Common Stock, par value $0.0001 (150,000)	—	—	150,000	Acquired
Oct. 1, 2025	ALT	Stock Options (option to buy)	Common Stock, par value $0.0001 (450,000)	$3.87	Oct. 1, 2035	450,000	Acquired
May 25, 2020	TPST	Stock Option (right to buy)	Common Stock (80,000)	$2.00	May 24, 2030	80,000	Acquired
Feb. 10, 2020	TPST	Employee Stock Option (right to buy)	Common Stock (140,000)	$6.90	Feb. 9, 2030	140,000	Acquired

Exercise/conversion price is blank when not applicable (e.g. RSUs).