The shape of the curve matters. In high interest rate environments, large companies borrow at a higher rate rate relative to smaller companies because the curve is flatter. In a low-interest rate environment, the curve is very steep, so large companies borrow cheap but small companies only borrow just slightly lower rate than they do in a high interest rate environments. Large companies are able to borrow at rates closer to the fed funds rate whereas small business borrows at am much higher rate. Low interest rates and cheap borrowing allows large businesses to expand and possibly crowd out smaller businesses, that have to borrow at much more unfavorable rates.