However, the labour market differs from other markets (like the markets for goods or the financial market) in several ways. In particular, the labour market may act as a non-clearing market. While according to neoclassical theory most markets quickly attain a point of equilibrium without excess supply or demand, this may not be true of the labour market: it may have a persistent level of unemployment. Contrasting the labour market to other markets also reveals persistent compensating differentials among similar workers.