Close of businesswoman making announcement in paper trumpet

The U.S. brokerage commission war escalated on Thursday when low-cost investing pioneer Vanguard announced it is expanding commission-free trading for Vanguard Brokerage clients.

The firm has extended its free online trading to include stocks and options, in a bid to further reduce the costs of investing. Vanguard already offers commission-free trading for many mutual funds and ETFs.

Last year, several U.S. online brokers slashed trading commissions to zero. In the wake of the price war, industry giants Charles Schwab and TD Ameritrade unveiled a planned merger.

Vanguard stressed that investors should consider the impact of other fees, expenses and opportunity costs in addition to trading commissions.

“The continued reduction and elimination of fees across the investment industry is a positive development for investors and one that Vanguard has long championed,” said Karin Risi, managing director of Vanguard’s retail investor group, in a statement.

“However, as we move to an environment in which ‘zeros’ dominate the headlines and explicit fees become implicit, we encourage investors to look more deeply at the total cost picture. Vanguard remains a vocal proponent of clear and transparent fee disclosure,” she said.