Weekend: a good time to make some general reflections about what we have been learning or deducing so far from the various experiences and tests. Feel free to jump in, adding your contributions and experiences...
Margin method: "RegT" vs "Portfolio margin"
Let's start from the account setup. We have seen that in practice the
RegT margin methods with
STKs and
ETFs is hardly viable as it places too "strict" restrictions. The consequence is that the already small funds (if one has large funds RegT is obviously meaningless) are quickly absorbed by the stk position, and one ends up
being forced to take losses pretty soon, even if the trades turn out to be done correcly.
However, the
porfolio margin method (
https://www.interactivebrokers.com/en/?f=margin&p=pmar) has a min
110K requirement, so in practice if you don't have a good risk capital, to maintain that figure even in DD, better forget about it.
Clearly the alternative would be either trading
FX (
https://www.interactivebrokers.com/en/index.php?f=margin&p=forex) or
futures (Span margin method:
https://www.interactivebrokers.com/en/?f=margin). However, trading futures with small funds, may not be a brilliant idea, and one can end up pretty badly. For the small trader, it remains FX. Here the problem is the absence of options (one could use the futures options, but would probably be too big), and also the general dynamic of the price curve which tends to have longer waves and relatively smaller inner fluctuations. Thus, long discouraging DD with little or no profits.
So, the general consideration would be: do not trade, unless you have suitable
risk capital. That is, funds that you can afford to lose, without it being a problem. If you don't have it, but still passionate about the field, the research and with money management, what I always suggest is to build up practical experience with a good trading tool (paper trading would also do fine,
provided the methodology and approach is convincing) and then, when mature, look for wise people with suitable resources, and especially "balls"

, to fund the venture and investment. Backtests are mostly a waste of time, or even worse,
strongly misleading, when they favor
curve-fitting activities (practically always), performed on a simple "projection" (the price dimension) of a complex multidimensional phenomenon. Trading is instead mostly a
live performing activity. Just like aerial combat, or a live concert

Much more useful and meaningful is instead a simulation activity, carried out to examine the deterministic aspects of the component represented by the non-predictive scalping/hedging game.
"Risk" capital
It is important to note that the funds used for trading, no matter if large or small, should be treated with
complete emotional detachment. That is, they must
not represent your pension or some "lifetime savings". Nor any aspect of your life must depend on it. The reason for that is, since there is no method which does not have some DD (well, raise your hand if you know one, that is not a backtest

), if you start feeling
anxiety and
stress when there is an "
investment phase" and you are in DD, that is a
sure way to lose. If you cannot remain emotionally detached from your capital being traded, you have actually already lost it,
even before start trading. That is sure 100%. In fact, given enough time, with finite funds and emotional attachment, there will always be a DD which will "convince" you take an unrecoverable loss. It's only a matter of time and frequency.
Ideal trading setting
It seems that the most suitable environment for this kind of activity is, after all, a
portfolio of liquid futures, with decent
risk capital. Liquid instruments with
liquid options should be the preferred choice. One or two FX pairs might also be included if there are large funds (we may be better off with the corresponding futures anyway). Most sectors are correlated so, in practice, the idea of "diversification", while appealing in principle, can be harder than expected to achieve in reality.
Never build a long term position against drift/decay/contango
It is important to carefully look at the "drift" that the instrument exhibits and make sure not to build a long term position against it. In fact, the decay would eat up any profit stemming from scalping activity, if the main position is systematically against it.
Watch the gaps and choose wisely the instruments
ETFs, as we have seen, offer a lot of challenges. Some of these are:
-
Drifts/ decay etc.: do not trade a long term position against the possible drifts
-
Non shortability: instruments are often non shortable causing great disruption in algorithmic trading and scalping activity. Also, for small price instruments, execution related issues may arise.
-
Margin: take too much margin and eat up quickly your funds (with portfolio margin the situation is slightly better)
- Possible large
overnight gaps: usually you don't want to
go overnight with a large exposure, so you may need to "flatten" the position. Problem is that if you were short, the next day you may not be able to re-open (pretty typical with ultrashort ETFs) and remain "trapped" in a large loss after a long and painful "investment".
-
Illiquid options: this can be a significant problem, since the spread is so large that practically once you make a transaction you are "trapped" in the position until expiration
FUTURES: best "bang for the buck" for speculative activity. Things that have to be watched:
-
Contango / backardation: do not trade systematically against them long term, or you will end up being eaten alive

-
Physical delivery (
http://ibkb.interactivebrokers.com/node/992) and
rollover: we have a few mechanisms in place to carry on the "
past trading information" (that is the player "logic") from an instrument to the next contracts, so this should not represent a problem at conceptual level
- Very
good "risk capital", because even just 1 contract has usually a pretty large multiplier for most instruments
Never make (large) "directional" bets: non-predictive scalping
The reason for that is, in hindsight

, pretty obvious. If one goes about trading by making systematically large
directional "bets" it is unavoidable that, given enough time, he will end up with some large loss beyond recovery, because
sooner or later funds will not suffice to sustain an unfavorable move. And, in any case, the DD can last a discouraging length of time, so an anxious investor could anyway
run out of patience and leave the money on the table,
even if the bet turns out eventually to be a winner (I have seen this several times).
One could argue: what about relatively "
high probability" trades and and "relatively
small stops"? Well here the discussion could become heated. I might start by saying with De Finetti that "
Probability does not exist"

(
https://faculty.fuqua.duke.edu/~rnau/definettiwasright.pdf).
Also, in a nutshell,
wherever you place your stop or take profit, by symmetry, ignoring the trading costs, you will end up in the long term, with the following relationship:
Avg profit / Avg loss = Prob Loss / Prob Profit
that is, essentially an "asymptotic" PNL = 0, with the commissions and spread (and possible other forms of "decay") adding a
strongly negative drift, which will be more evident as the trading frequency increases (with less frequent trades it easier to quickly "
curve fit" by computer and get
self-deceiving simple "strategy", which essentially ends up making more trades in the prevalent direction of the instrument, during the chosen backtest period: typical naive
curve-fit with a 45-degree equity curve

).
(Actually when the stops get really "small", the relationship may actually break into a even more unfavorable one, giving rise to the so called "
death by thousand cuts".)
This, in essence, is saying is that there is no real reason why the value of profitable trades will exceed the value of losing trades,
just by effect of how you choose the take profit and stop distances. It is obvious that it is so, because, apart there is
no reason for that to happen, if such a "regularity" existed in a mkt it would be readily discovered and exploited, leading to the extinction of the specific mkt, which is not the case, as instead
who get extinct are rather the traders 
But, anyway, try that, and let me know
The truth is that you could be "
guaranteed" to be profitable beyond any limit only if an instrument were trading within a "finite" (and "relatively" small) range, like for instance a stochastic process evolving continuously within "
reflecting barriers" (e.g.,
http://en.wikipedia.org/wiki/Reflected_Brownian_motion). In that case, it is obvious that you could make unlimited profits just suitably buying and selling within that range (there would be no need of any "prediction"). Problem is that obviously such instruments
do not exist, as if they existed the relevant mkt itself would quickly disappear. So, what we can do is to subdivide the price move into approximately "horizontal segments" (where a profit can be actually extracted through
non-predictive scalping/hedging), while finding ways to
hedge against the vertical component (which can carry either a "loss" or a "profit" on "reversion" to a previous "horizontal" level.)
[continues...]