noun which may take the genitive case particle 'no'
independent; unaffiliated; self-funded
Describes an organization, group, or entity that operates independently, without affiliation to a larger parent body, and often self-funded. Common in business, media, and political contexts.
彼は独立系の調査機関で働いている。
He works for an independent research organization.
That newspaper is independent and not affiliated with any particular political party.
系列 refers to a corporate group or affiliated chain; 独立系 is the opposite, indicating no such affiliation.
Compound of 独立 (independence) + 系 (system, lineage, group). The term likely emerged in modern business and media contexts to describe entities not belonging to a larger keiretsu or conglomerate.