SPERO THERAPEUTICS, INC.
SPERO THERAPEUTICS, INC. is a Public Limited Company registered in United States under 001137788, and its current status with Massachusetts Secretary of the Commonwealth is active. The company was incorporated on 29 May 2014 and lists its registered address as United States. 2 shareholders are on record for SPERO THERAPEUTICS, INC., and since every one of them is a company rather than an individual, this particular filing does not on its own establish an ultimate beneficial owner (UBO) — identifying one would mean tracing the ownership of each shareholding company in turn. This profile is sourced directly from Massachusetts Secretary of the Commonwealth and was last updated on 5 October 2026.
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Shareholders
2
Two shareholders are currently on record for SPERO THERAPEUTICS, INC., reflecting the stock ledger maintained under state corporate law (e.g. §219 of the Delaware General Corporation Law) rather than a public filing.
The largest of these is Vanguard Group Inc, holding 16.9% — the largest recorded stake — followed by Adar1 Capital Management, LLC at 6.2%.
Because every shareholder shown is a company rather than an individual, the ownership chain continues above this level, and no beneficial owner can be established from this filing alone.
| Shareholder | Type | Holding | Source Document |
|---|---|---|---|
| Vanguard Group Inc | 16.9% | Massachusetts Secretary of the Commonwealth | |
| Adar1 Capital Management, LLC | 6.2% | Massachusetts Secretary of the Commonwealth |
Officers
5
The Ceo, Cfo, President, Treasurer & Director of SPERO THERAPEUTICS, INC. currently on record is Esther P. Rajavelu; five officers are currently on record for SPERO THERAPEUTICS, INC., filed with Massachusetts Secretary of the Commonwealth.
The register reports 15 officers in total, including past appointments, though only the 5 most relevant records are shown here.
Management authority at SPERO THERAPEUTICS, INC. sits with these individuals, not with shareholders, who are covered separately and hold ownership rather than control.
The source filing doesn't specify representation authority — whether officers can act individually or must sign jointly to bind the company — so that detail isn't available here.
Group Structure
SPERO THERAPEUTICS, INC. has no recorded parent company — it sits at the top of its own group structure, with 7 subsidiaries recorded beneath it across 2 jurisdictions. Each of these downward relationships is derived rather than filed: resolved by matching entities across the registry network, not stated directly in a single document.
Those 7 subsidiaries span United States, United Kingdom jurisdictions, though this list should not be read as complete — subsidiaries only become visible here where shareholder data has actually been filed with a register, so holdings in jurisdictions without that filing simply won't appear. One of the 7 go a level deeper still, with its own further subsidiaries recorded beneath it — additional ownership layers this view doesn't expand.
SPERO THERAPEUTICS, INC.
United States
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Frequently Asked Questions
Who owns SPERO THERAPEUTICS, INC.?
Two shareholders are currently on record for SPERO THERAPEUTICS, INC., reflecting the stock ledger maintained under state corporate law (e.g. §219 of the Delaware General Corporation Law) rather than a public filing. The largest of these is Vanguard Group Inc, holding 16.9% — the largest recorded stake — followed by Adar1 Capital Management, LLC at 6.2%. Because every shareholder shown is a company rather than an individual, the ownership chain continues above this level, and no beneficial owner can be established from this filing alone.
Who is SPERO THERAPEUTICS, INC.'s UBO (Ultimate Beneficial Owner)?
Every shareholder recorded for SPERO THERAPEUTICS, INC. is itself a company rather than a natural person, so no Ultimate Beneficial Owner (UBO) is identified at this level; establishing one would require tracing the ownership of each shareholding company in turn.
How many shareholders does SPERO THERAPEUTICS, INC. have on record?
2 shareholders are shown on record for SPERO THERAPEUTICS, INC..
What is SPERO THERAPEUTICS, INC.'s company registration number?
SPERO THERAPEUTICS, INC.'s registration number is 001137788, filed with Massachusetts Secretary of the Commonwealth in United States. Its current status on the register is active.
Is SPERO THERAPEUTICS, INC. still an active company?
SPERO THERAPEUTICS, INC.'s status on Massachusetts Secretary of the Commonwealth is listed as active.
When was SPERO THERAPEUTICS, INC. incorporated?
SPERO THERAPEUTICS, INC. was incorporated on 29 May 2014, according to Massachusetts Secretary of the Commonwealth.
What is SPERO THERAPEUTICS, INC.'s registered address?
The registered address on file for SPERO THERAPEUTICS, INC. is United States.
What legal structure is SPERO THERAPEUTICS, INC. registered as?
SPERO THERAPEUTICS, INC. is registered as a Public Limited Company in United States.
Who are the officers/directors of SPERO THERAPEUTICS, INC.?
The Ceo, Cfo, President, Treasurer & Director of SPERO THERAPEUTICS, INC. currently on record is Esther P. Rajavelu; five officers are currently on record for SPERO THERAPEUTICS, INC., filed with Massachusetts Secretary of the Commonwealth. Management authority at SPERO THERAPEUTICS, INC. sits with these individuals, not with shareholders, who are covered separately and hold ownership rather than control.
Does SPERO THERAPEUTICS, INC. have a parent company or subsidiaries?
SPERO THERAPEUTICS, INC. has no recorded parent company — it sits at the top of its own group structure, with 7 subsidiaries recorded beneath it across 2 jurisdictions. Those 7 subsidiaries span United States, United Kingdom jurisdictions, though this list should not be read as complete — subsidiaries only become visible here where shareholder data has actually been filed with a register, so holdings in jurisdictions without that filing simply won't appear. One of the 7 go a level deeper still, with its own further subsidiaries recorded beneath it — additional ownership layers this view doesn't expand.
Can Zavia monitor changes to SPERO THERAPEUTICS, INC.'s ownership over time?
This profile reflects a point-in-time snapshot from Massachusetts Secretary of the Commonwealth. Zavia's monitoring API can track changes to SPERO THERAPEUTICS, INC.'s registered shareholders, officers, and group structure going forward, flagging updates as they're filed rather than requiring a manual recheck.
Can I access SPERO THERAPEUTICS, INC.'s data through an API?
Yes. Zavia's API connects directly to official government ownership registries across 195 countries and territories, including United States, so records like SPERO THERAPEUTICS, INC.'s registration, shareholder, UBO, and group-structure data can be queried programmatically instead of viewed one page at a time.
Where does this company information come from, and how current is it?
This record is sourced directly from Massachusetts Secretary of the Commonwealth and was last synced on 5 October 2026.