Answer:
Inefficient.
Step-by-step explanation:
Market efficiency can be defined as a measure of the degree to which prices in a market reflect all available and significant information at a specific period of time. A market is said to be efficient when all information has been incorporated into the prices of goods and services, and as such it is impossible to "beat" the market because there are no overvalued or undervalued stock.
Hence, when markets are inefficient, investors could use available information ignored by the market to earn abnormally high returns because the market doesn't reflect the all the informations such as the fair and true market value of assets.