One reason to avoid thinly traded stocks is that they seldom attract institutional support. High-skills staffing provider On Assignment (ASGN) is an exception to that general observation. The stock trades about 302,000 shares daily, shy of the 400,000 level that separates the thin from the sufficiently traded. However, the stock has been attracting fund support. In the first nine months of last year, funds holding shares rose from 262 to 313.