All major firms offer their customer on-line services, such services include discounted trades. So you should select a large well known firm.
It seems that the most popular firms for on-line investing/trading all of which provide excellent platforms and services are; Scottrade; Chas.Schwab; TDAmeritrade; Fidelity; E-Trade, Vanguard, T.Rowe Price and Thinkorswim. In your situation, you may be best served if you select Scottrade or Ameritrade
fidelity $7.95 a trade
I'm looking for a good discount broker with low fees. any good ones out there?
