Any time you see a 14.9% dividend yield, it is likely too good to be true. If that dividend was stable and growing, then a horde of investors would buy shares, pushing the price up and the dividend yield down. Sure enough, high-yielder Apollo Investment ( AINV) sports an unsustainably high dividend. From fiscal (March) 2007 through 2009, this investment fund, which must pay out 90% of its income to avoid taxes, offered up a roughly $2 annual dividend. That dividend has fallen to around $1 more recently, and in coming quarters, the annualized payout may slip closer to 75 cents or 80 cents. That's because the firm's current slate of holdings aren't generating the returns to keep the payout above $1. Let's assume the dividend falls to just 75 cents a share. That still equates to a 10% dividend yield. In response to a potential drop in the payout, investors have been selling, pushing AINV down from $12 last spring to a recent $7.50. That's below the $8.12 a share in book value, implying tangible downside support at current levels.