William Blair acted as exclusive financial advisor to ENTEK Technology Holdings LLC (ENTEK), a portfolio company of Endeavour Capital (Endeavour), in connection with today’s announcement that I Squared Capital (I Squared) has agreed to acquire a majority equity interest in the company. The transaction was signed on August 15, 2025, and is expected to close following regulatory approvals and the initial Department of Energy (DOE) loan drawdown. This pending $800 million investment made by I Squared complements a $1.2 billion loan made by the U.S. DOE Loan Programs Office, with initial funding provided today, that will accelerate the construction of the first and only U.S. gigafactory for wet-process lithium-ion battery separators in Terre Haute, IN.
About the Companies
ENTEK has 40 years of experience producing battery separators for batteries to support electric, advanced start-stop and standard vehicles, trucks, emergency vehicles, emergency backup power, utility scale energy storage, and industrial batteries. The company has nearly 25 years of experience as the only U.S.-owned and U.S.-based producer of ‘wet-process’ separator for lithium-ion batteries and continues to invest in the future of the domestic lithium-ion battery industry. ENTEK is also a vertically integrated designer and manufacturer of extruders and material handling equipment for the production of battery separators and many other non-ENTEK applications.
Endeavour was founded in 1991 to be a patient source of capital and long-term partner to leading private businesses and management teams. Today, the firm is investing its eighth fund and has offices in Los Angeles, Portland, Seattle, and Denver. Endeavour invests in Western U.S.-based companies in partnership with founders, family owners, and executives. The firm acts as partners and stewards to help companies and their owners realize their potential while preserving legacy and culture.
I Squared is a leading global infrastructure investor managing $45 billion in assets. The firm builds and scales essential infrastructure businesses that deliver critical services to millions of people worldwide. The firm’s portfolio includes over 90 companies operating in more than 70 countries and spanning sectors such as energy, utilities, digital infrastructure, transport, environmental, and social infrastructure. Based in Miami, I Squared has a team of over 300 professionals based across offices in Abu Dhabi, London, Munich, New Delhi, São Paulo, Singapore, Sydney, and Taipei.
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