market player

米連邦公開市場委員会（ＦＯＭＣ）は20日午前３時に声明と最新の景気予測を発表します。世界の株式市場などが不安定な動きを続けるなか、ＦＲＢのバーナンキ議長の会見での発言に注目が集まっています。

Market playersには定訳はないようですが，Financial Times Lexiconには"A company or financial institution involved in a particular market."とありますので，「市場関係者」あたりでしょうか。（Haramii）
http://lexicon.ft.com/Term?term=market-player

Bernanke in spotlight when Fed meeting ends

Market players across the globe are paying close attention to what Federal Reserve chairman Ben Bernanke
will say after the central bank ends its 2-day policy meeting on Wednesday.

Their focus is on how long the bank aims to maintain its current monetary easing to support the US economy.

Market participants warn that Bernanke's comments on the question may turn global financial markets volatile.

http://www3.nhk.or.jp/nhkworld/english/news/20130619_32.html