I have been using Interactive Brokers for an year and a half now, trading stocks and cfds and I have been largely successful, almost 70% return on my investment. The spread between the bid and ask price for the stocks I have traded has always been in the range of a few cents.
However I noticed recently that this spread has increased to 40c, 50c, even more for certain stocks.
IB are denying that anything has changed in my account but somehow I do not trust them.
So my question is, can they legally manipulate the spread, so that they take a larger chunk from my trades? They claim that the bid and ask price are determined solely by the market. But is this really the case? Other online brokers have their own spreads.