Selling into a market that is going up. For instance, if crude oil is at $37 a barrel, you would sell some crude at $37, then at $38, and then at $39. Often producers of oil, who own the actual commodity, employ this strategy. They know what their costs are and they are locking in a rate of return on their investment. However, at some point the market may continue trending upward, which may produce a margin call at $45. It can be a risky trading strategy, unless the trader has a good sense of what ranges prices will remain in. This term is typically used in the futures market.