If the S&P 500 rallies for multiple days and your stocks do nothing. You might be witnessing a secular decline. Half of a stocks performance can be attributed to the sector that it belongs to. The rest of a stock’s performance is based on earnings of your particular company.
However, if the market rallies over multiple days and your stock remains stagnate, you had better sell (Channel your inner Bill Engvall: Here’s your sign!). This is a red flag that your stock has little support when the market decides to correct. Even if you believe the stock is undervalued already or that there is a catalyst on the horizon, get out and come back later when the sector is back in favor.