February 21st, 2005, 3:48 pm
QuoteOriginally posted by: mrbadguyThis paper gives you a brief sum of statistical method for b-a spread analysis in commodity futures marketI'd be curious to see a rigorous analysis of the trendiness of last-trade prices, as a function of the bid-ask spread.As a trend trader, I used to click around looking for charts where an uptick was likely to be followed by another uptick. More often than not, when I found such a chart, the bid-ask spread made trend trading it ridiculous.A pretty good argument can be made that all phenomena in nature - even those that mean-revert, such as the daily temperature - are trendy in most time frames. As such, price charts are originally trendy, until the scalpers at Schonfeld securities chop them up with whipsaws.Therefore, how much the original trendiness has survived, is a good measure of whether some day trader has found it worth his while to try to pick off limit orders. The fact that wide-spread markets remain trendy, confirms the advice of day traders to avoid them. Their trendiness is evidence that trend traders have avoided them.Still, I remember when I was a SOES bandit in 1993 at All-Tech in Suffern. Nobody would touch Newbridge Networks (NNCXF) with a 2-point spread, or Oxford Health (OXHP?). But being something of a hardhead, I traded it anyway, and made money every time (if I remember correctly).Anyway, it is hardly possible for a choppy market to survive a wide bid-ask spread. People will quickly learn it is choppy, and will place competing limit orders to try to catch the reversals. Or, those who place limit orders will tend to increase their size as they get wealthier (exceptions occur where there is some payment flowing to the original exposers of the free options that are limit orders, where this payment is enforced in the form of a large minimum increment, and where there is something other than time priority).And if volatility is constant, then the immediate bid-ask spread can be used to price options, where such options will be underpriced relative to low-frequency volatility, and will sell in boatloads until dynamic hedgers swamp the market and widen the spread in a sort of self-correcting mechanism.But anyway, a wide spread just means the minimum increment is too small. Raise the minimum increment, and enforce time priority (not a pit), and your market will trade the same as any other. If it moves more relative to the absolute price that is irrelevant, as is the fact that it moves more slowly (ignoring the value of alternative uses of your time).
Last edited by
farmer on February 20th, 2005, 11:00 pm, edited 1 time in total.