A principal member of the stock exchange who buys and sells securities on his own is a
jobber
promoter
broker
speculator
Correct answer is A
A jobber is a principal or wholesaler who deals only on the Stock Exchange with brokers, not directly with the public.
A stock jobber holds shares on their own books and created market liquidity by buying and selling securities, and matching investors' (buy and sell orders through their brokers, who were not allowed to make markets)