米国通貨を大量に売っている投機筋に対抗して、主要国の中央銀行は市場で大規模な協調介入を行った。

、。

To counter speculators who were selling large amounts of U.S. currency, the central banks of major nations carried out a large-scale coordinated intervention in the market.

Literal

American currency [object-を] large-volume selling speculators [against-に対抗して], major-nations' central banks [topic-は] market [in-で] large-scale coordinated intervention [object-を] carried-out.

An extremely dense sentence packed with financial terminology: 投機筋 (speculators), 協調介入 (coordinated intervention), 中央銀行 (central bank). The ~に対抗して structure means 'in opposition to.' This is real newspaper-level financial Japanese, useful for advanced learners targeting business/finance reading.