We provide an axiomatic treatment of the measurement of economic insecurity, assuming that individual insecurity depends on the current wealth level and its variations experienced in the past. The first component plays the role of a buffer stock to rely on in case of an adverse future event. The second component determines the confidence an individual has on her ability to overcome a loss in the future. Two classes of linear measures are characterized with sets of plausible and intuitive axioms and, for each of these classes, an important subclass is identified.