θ measures the sensitivity of option price to time change, and indicates how much the option value will be lost every day when other factors remain unchanged.

θ value mainly has the following meanings:

(1) For 50ETF options, generally speaking, when there are two weeks left in the expiration time, the time value of the option near the flat value begins to accelerate. Therefore, for option buyers, unless you have a strong grasp of the trend of the underlying assets, the cost of buying contracts near the fair value is very high at this time, because the daily time value is greatly lost. At this time, you can consider buying deep real value options because the loss of time value is small.

(2) For investors who make a buy-and-span strategy, if they bet on the increase of implied volatility and make a buy-and-span, they can consider the far-month contract, because the far-month contract vega is larger and Theta is smaller; Investors with large directional changes in the underlying assets in the short term may consider approaching the maturity contract, but the position should not be too heavy, because θ and γ are both large at this time, and the daily time value is greatly lost. However, if the underlying assets really change greatly, the income is also high.

(3) For option sellers, if the current volatility is at a historical low level and the value of virtual contracts in recent months is already very low, it is not cost-effective to be a seller at this time. You can consider selling virtual contracts next month, so the time value of virtual contracts next month is higher and Theta is greater. If the current implied volatility is at a relatively low level in history, the premium of the virtual contract in the current month is already very low, and the seller is unprofitable, we can consider gradually moving the position to the virtual contract next month.