By that I don't mean just "How is HSX doing?" We'd need something more specific. Even the Indexes you see reported in the news are not All Stock Market indexes. The DJ Industrial Average is just that, an average of certain Industrial manufactoring companies. NASDQ is likewise a specially selected sampling of certain stocks in that market.
Next we have to keep in mind that unlike a real world stock exchange, shares in HSX are not a limited resource. And they are specifically and precisely defined price-wise to external markers, the same is not true of real stocks. Finally many HSX securities have a limited life, they are on the market for a relatively short time and then disappear; real stocks last as long as the company they represent ownership in lasts. (In that way HSX MovieStocks are more like Bonds, while HSX StarBonds are closer to real world Stocks.) Those things make HSX securities behave differently than real money stock markets.
Okay, that said, ForceIndia you said you wanted a snapshot of the overall market direction. Can you be more specific? If not then my first thought would be to average the change in price of all Moviestocks on HSX. That might give one a day to day feel for whether people are buying/covering or selling/shorting Movies. (We'd have to exclude Moviestocks that adjust or delist from that day's average since those price changes have nothing to do with player transactions.) If you want a longer view average of how much money movies are making, maybe averaging the TAGs of all the Starbonds would do it.