Jobber

A trader that trades for short term profits that are small during any trading session is known as the jobber. A jobber closes trades between hours and they very rarely carry the trade overnight to the next day.
A jobber broker mostly deals in day orders where the orders are executed in the day based on the criteria specified by the investor.  If during the trading day the condition required by the investor is not seen in the market, then the order is not executed and it is allowed to expire.
Though a jobber makes very small profits in a day, it does not mean that he trades easily.  Being a jobber is very difficult because they need to be a close watcher and technically analytical to catch hold of tiny changes in a highly volatile market to get that small profit.
A jobber is a meticulous trader; in fact they are market makers.