t为什么是0.9除0，31

晚上好，在梁老师的第9节视频 Hedging and FX中的02:30~02:35之间提到了，只要basis放大，一定会形成spot price上升, future price下跌。此处存在些许疑问，比方说，spot price下跌，future也下跌，但future下跌的幅度更厉害。这种情况不也一样会造成basis放大吗？

为什么股票是y 指数是x

请问老师，书上这段没有看懂，可否解释下，多谢 The basic premise of APT is that investors can create a zero-beta portfolio with zero net investment. If such a portfolio yields a positive return, however, then a sure profit can be real-ized through arbitrage. The fundamental result, as proved by Professor Ross, is that the absence of arbitrage opportunities requires the expected return on all well-diversified portfolios to satisfy E(RP) = E(RZ) + bP1[E(I1) - E(RZ)]+ c +bPK [E(IK) - E(RZ)] where RP is the return on a well-diversified portfolio with expected return E(RP); bPk is the factor loading for the portfolio P related to factor k; E(RZ) is the expected rate of return on the zero-beta port-folio (i.e., the risk-free rate) such that Cov(Ik, RZ) = 0, for k = 1, c,K; and E(Ik) - E(RZ) is the risk premium associated with factor k.

老师、请问下为什么market portfolio的系统性风险为1呢。是无论什么情况下均为1吗？谢谢

老师 习题集277题，计算股票一年后的价格区间时，计算置信区间 为什么直接拿标准差乘以关键值，而不是标准误呢？

这页是价值还是价格的比较

这页是价值还是价格的比较

d/f=eur/usd，老师这里的写法错了

for arbitragers, why they need to borrow money, buy asset and short futures, instead of using their cash to buy assets and short futures?