Second, the factors that affect the cost of holding change. Theoretically, the futures price is equal to the spot price plus the holding cost, which mainly includes storage cost, insurance cost, capital cost and loss. If the holding cost changes, the basis will also change, thus affecting the profit and loss of the hedging portfolio.
3. The mismatch between the hedging risk assets and the underlying assets of the hedging futures contract. There was no soybean oil futures contract in China before 2006. Because of the high correlation between soybean price and soybean oil price fluctuation, soybean oil producers or consumers use domestic soybean futures contracts to hedge soybean oil prices, which is called cross hedging. The basis risk of cross hedging is the biggest, because its basis consists of two parts, one part comes from the difference between the futures price and the spot price of the hedged asset, and the other part comes from the difference between the spot price of the hedged asset and the spot price of the hedged asset. Because the hedged risk assets are different from the underlying assets of the hedged futures contract, the basic factors affecting the price change are also different, resulting in a relatively high basis risk of cross hedging.
4. Random disturbance of futures price and spot price.
Due to the above four reasons, during the holding period of the hedging portfolio, the basis continues to expand or shrink, which makes the hedging portfolio generate profits and losses. Under normal market conditions, because the factors affecting the spot price of assets are the same as the futures price, the fluctuation range of the hedging basis is relatively small and stable in a fixed fluctuation range, and the profit or loss of the hedging portfolio generated within this fluctuation range is small, so it will not have much impact on the effectiveness of hedging. However, in some special cases, there will be abnormal situations that are not conducive to hedging in the market, which will lead to the continuous expansion or contraction of the basis of hedging, resulting in increasing losses of hedging portfolio. If the stop loss is not stopped in time, it will cause huge losses to the hedger. In terms of probability, the abnormal basis biased towards the normal basis level is a small probability event, but if the risk of this small probability event is not handled properly, hedging will cause huge losses.