The primary objective of this paper is to evaluate the association between market value and cash flow ratio, and to understand how economic instability alters it. Because this relationship is cross-temporal and may change if other financial indicators are considered, we model this relationship via multiple functional linear regression. We conclude from our multiple sectors study that market value ratio is affected by or follows cash flow mostly during the same time period and that this association weakens considerably under economic instability. We also show that for some industry sectors, while other financial indicators may drive market value, cash flow is likely to be the key player in most sectors.