As per the proven academic hypothesis by Ilmanen(2003), it has been established that in times of growth uncertainty, low inflation and stable discount rates, there is an inverse relationship between Bond Yields and Equity Markets. The simple logic behind it is that, investors are looking for risk free return and if the dividend yield of index which is on average 1.74% for Nasdaq with risk (In Feb 2021 it was 1.34%), is lower than risk free investments i.e. bond then why invest in Equities?
This is the reason why the equities have started to fall now as bond yields are rising. Bond yields have been rising since August 2020 but their yields were not high enough as compared to Equities. Now when the yields are higher than the dividend yield on equities, people have started to invest in bonds.
The same is the case with Gold. Holding gold does not give any return but bonds do and being risk free, offering a higher return than equities, ergo, people have again started to invest in bonds by shorting Gold.