The 1840s British investment mania centered on railway companies was called Railway Mania.
Railway Mania developed in Britain as investors became excited about the commercial possibilities of rapidly expanding rail transport. Parliament approved many new railway schemes, and share prices rose as people speculated on future lines and profits.
The boom encouraged genuine infrastructure construction, but many projects were financially weak or overly optimistic. When confidence deteriorated, railway shares fell and investors suffered heavy losses.
Railway Mania is an early example of a speculative investment bubble connected to a transformative technology. It is often compared with later bubbles involving automobiles, telecommunications, or internet companies, although the railway boom also produced lasting physical infrastructure.