Rolling stock originally referred to the vehicles that move on a railway. It has since expanded to include the wheeled vehicles used by businesses on roadways. It usually includes both powered and unpowered vehicles, for example locomotives, railroad cars, coaches, and wagons. However, in some countries (including the United Kingdom), the term is usually used to refer only to unpowered vehicles, specifically excluding locomotives which may be referred to as running stock, traction or motive power.
Rolling stock is considered to be a liquid asset, or close to it, since the value of the vehicle can be readily estimated and then shipped to the buyer without much cost or delay.
The term contrasts with fixed stock (infrastructure), which is a collective term for the track, signals, stations, other buildings, electric wires, etc., necessary to operate a railway.
As per MarketsandMarkets analysis, Market size of rolling stock market in terms of value is estimated to be at $38.5 billion in 2014, which is projected to grow to $45.7 billion by 2019 at a CAGR of 3.48%.