证券 (zhèngquàn) means "securities" and refers to financial instruments such as stocks and bonds. It commonly appears in formal and financial contexts, as in 证券交易委员会 (Securities and Exchange Commission). The word combines 证 (certificate) and 券 (ticket/coupon).
他在一家证券公司工作。
Tā zài yī jiā zhèngquàn gōngsī gōngzuò.
He works at a securities company.
最近证券市场的波动很大。
Zuìjìn zhèngquàn shìchǎng de bōdòng hěn dà.
The securities market has been very volatile recently.
她考了证券从业资格证。
Tā kǎole zhèngquàn cóngyè zīgé zhèng.
She passed the securities industry qualification exam.