Alex, No, without knowing all specifics, I could not claim specific manipulation at Interactive Brokers. However, to expand upon Interactive Brokers a bit, it is a matter of public record that Interactive Brokers was disciplined and fined by the National Futures Association in separate instances for failing to supervise large volume traders and for transacting business with unregistered individuals. Would a more rigorous review have identified criminal backgrounds in these unregistered individuals? Would more granular supervision of large volume traders have further identified their manipulative trading patterns? If the examiners identified these issues at the firm in sampling alone, then I believe there is more than a reasonable chance that manipulation is occurring or has occurred in the firm's total population.

I think a large reason why FX will never be fully centralized is due to the nature of money itself. Nation states value their own sovereignty and the 'majors' G7 and G20 nations already do a lot to shape the worldwide monetary policy. Credit is very complex in the sense that there is no one-size-fits-all solution to orderflow. It's a ponzi scheme, but a ponzi that citizens agree to and agree with the majority of the time, so it keeps running as long as new blood continues to have confidence of the usefulness of the credits (and fear of not having). Trading Fx helped me to understand just how money works and how fragile the credit system really is.

And in regards to Alex's comment about market orders being a poor choice for fx trades, this depends on your strategy and speed of execution. There is a tradeoff between limits and market orders. Limit orders guarantee a certain price, but do not guarantee immediacy or a fill. Market orders guarantee a fill and near immediacy, but the price may be undesirable. We do not have hindsight and there are many times in volatile situations where immediacy trumps ideal price. If you do not get in at your limit, you may miss the significant part of the move which you were trying to take advantage of in the first place. Aggressive market orders should primarily be used by more informed traders.

With sell-side speculation, if you are trading counter-trend (sell while the market is moving upward and buy while the market is moving down), the slippage is positive on avg. Obviously for the buy side, it is negative. But the buy side, they are ok with this because they are trying to offload risk to sell side anyway and will pay for immediacy, including slippage.

Sorry for a delay with my reply, I started to write my answer but then deleted it as it became too lengthy for a comment in a discussion. Finally I wrote an article where I tried to address most of the concerns expressed in this discussion and posted it here: https://www.linkedin.com/groupItem?view=&gid=1813979&type=member&item=5915438359940968450&trk=groups_most_recent-0-b-ttl&goback=%2Egde_1813979_member_5911233316731777025%2Egmr_1813979

Dr Paul "This is like saying, when the bookies are open one can go and place a bet and if they were open 24 hours a day, we'll be able to place a lot more bets and come out as winners. The fact that FX markets are open 24 hours a day does not make the risks go away or turn ordinary people into supreme money spinners. Over 90% of day traders lose money."

No-one said trading at night time will make ordinary people into winning traders. But if trading at night is your preferred option, then having this ability should in theory give you better results (whether or not you are a winning or losing trader is irrelevant in that).

FX is no easier or more difficult than any other market, you need an edge greater than transaction costs to make money. Higher liquidity increases market efficiency, decreasing the possible edge but also decreasing transaction costs.

Provided one can always win. If not, it is only a casino open 24x7.