I think there could be infinite sets of portfolios because is infinite collection of asset selections and percentage allocation and no one can really draw the efficient frontier so this is the imaginary shape and no one can sure if efficient frontier is half of hyperbola. (money.stackexchange.com)
Given the X is below the hyperbola, it looks like I'm not getting properly compensated for the risk I'm taking. (financialsamurai.com)
«These mirrors have elliptical and hyperbolic shapes on a single substrate, and fixing of the relative positioning between the ellipse and the hyperbola can provide high image quality with lasting stability.» (sciencedaily.com)