Small-caps and large-caps are wildly popular among investors; however, mid-cap stocks, such as SEEK Limited ( ASX:SEK ) with a market-capitalization of AU$7.4b, rarely draw their attention. While they are less talked about as an investment category, mid-cap risk-adjusted returns have generally been better than more commonly focused stocks that fall into the small- or large-cap categories. Today we will look at SEK's financial liquidity and debt levels, which are strong indicators for whether the company can weather economic downturns or fund strategic acquisitions for future growth.