Curbstone Broker

Entry in progress—B.P.
 
(Oxford English Dictionary)
curb-stone, kerb-stone
attrib., as curb-stone broker (U.S.), a broker, not a member of the stock exchange, who transacts business in the streets; also curbstone agent, operator.
1848 W. ARMSTRONG Stocks 7 This class comprehends..all those petty operators and non-descripts, who have neither a local habitation or scarcely, a name, that are dignified by the title of curb-stone brokers.
1860 in BARTLETT Dict. Amer.
1861 Knickerbocker LVII. 635 All sorts of brokers, from the leading houses down to the curbstone ‘operator’.
1862 R. B. KIMBALL Undercurrents (1868) 321 It is rather a habit with the Curbstone operator when he gets severely winged, to go into the cigar business.
1884 Cent. Mag. Aug. 629/2 Peddling ‘privileges’ to small speculators through curb-stone agents.
1886 Pall Mall G. 28 May 14/1 Both of these men are kerbstone brokers. 
 
22 December 1854, Albany (NY) Evening Journal, pg. 2:
The anxiety to hear Mr. Benton lecture at Boston was so great that tickets of admittance sold at a premium equal to that demanded by a curbstone broker for shaving a note.
 
Google Books
Bulls and bears of New York: with the crisis of 1873 and the cause
By Matthew Hale Smith
Hartford, CT: J.B. Burr
1875
Pg. 71:
“CURBSTONE BROKERS”
These operators are sometimes called gutter-snipes. They do business outside of the Stock Board. They (Pg. 72—ed.) have no office, but operate on the street. They are small traders in stock, and are usually employed by brokers on small commissions. They buy and sell through others. Noted Bulls and Bears cannot attend the Stock Board without creating an excitement. They keep out of sight and employ these men. Parties who have not money enough to buy a dinner, often take a million of gold, or a thousand shares of stock. Curbstone brokers do not touch the gold, nor receive the stock. They simply stand between the broker and his customers. A large portion of this class earn only a scanty living. Most of them are reduced speculators, who haunt the street, hoping that fortune may change. many of this class rode in carriages when the present millionaires of New York were errand boys, or bootblacks, or porters.
 
Google Books
Dictionary of Americanisms: a glossary of words and phrases usually regarded as peculiar to the United States
By John Russell Bartlett
Boston, MA: Little, Brown and Co.
1889
Pg. 163:
Curb-Stone Brokers. Stock-operators, whose place of business is on the edge of the pavement in the vicinity of the Merchants’ Exchange, and whose account-books are said to be kept in their hats. “This is a very large class of speculators, and is composed of the oldest and most experienced operators in the street [Wall Street, New-York]. Many of them have been members of the Stock Exchange, but from having failed to fulfill their contracts during some of the numerous ups and downs of the market have been compelled to vacate their seats, and lost their membership. The curb-stone brokers have leased a large room directly under that occupied by the regular board; and during the session of the board a communication is kept up between the rooms, so that any transaction is known below as soon as made. Upon information derived in this way, the curb-stone brokers operate among themselves, and frequently with, and for the account of, the outsiders. This class of speculators are particularly fond of operating in ‘puts’ and ‘calls,’ and in fact resort to all the different methods of doing a large business on a small capital.”—Hunt’s Merchant’s Mag., Vol. XXXVII.
 
A more recent name for curb-stone brokers is gutter-snipes. 
 
OCLC WorldCat record
The curbstone brokers : the origins of the American Stock Exchange
Author: Robert Sobel
Publisher: Washington, D.C. : BeardBooks, 2000.
Edition/Format: Book : English