Who is Harding Brothers from Reminiscences of a Stock Operator and what is their importance?

This is the brokerage where Livingston first goes upon arrival in New York City, in addition to Fullerton's. Later, he returns to Harding Brothers when he is much more experienced, and becomes one of their star customers. He is a very active trader and they earn good commissions on his trades. On the occasions when he loses a lot of money and is wiped out, they are familiar enough with his skills to back him in trading again, sometimes requiring a little persuasion if the market movements are not as obvious to them as they are to Livingston. Harding Brothers also has brokerage houses in other cities, such as Atlantic City and Palm Beach, which Livingston often visits while on vacation.