The phrase "big tailwind" means having a strong and favorable wind blowing from behind. It metaphorically refers to a situation or condition that helps or supports progress and success in a significant way. Full definition
A weaker dollar and rising interest rates are two big tailwinds for small caps, and there are plenty that epitomize the opportunities available to savvy investors. (investorplace.com)
«The reason why this is likely to play out this year is the trifecta which has been driving global stocks over the last 12 - to - 18 months as a big tailwind is now bound to turn into a headwind.» (cnbc.com)