Anyone consistently trade in 10,000 share blocks of stock? I would stick with stocks on the S&P 100 until your more experienced. The majority of them keep a tight & constant spread of 1 cent or less and filling 10k shares typically takes less than a second - at least that's always been my experience when using a marketable limit order. These stocks your not going to get mugged getting in/out & have the potential to make large profits. I never hide my order size since I am only in highly liquid equities/ETFs - I see no benefit if your trading highly liquid instruments. Hidden orders get filled last. If your going to trade 10k shares you may want to consider using the IEX if your broker provides access. it can save you a lot of money. http://www.beathft.com/?p=13
selling into a spiking 8 minute RSI or similar / buying into a temporary low also helps keeping slippage low
No, it's not. I suspect that's what you guessed and present it as fact when it's not. Credit Suisse AES, Jefferies algos are offered by IB. That's just one example.
Answer is, it depends. Someone already mentioned SPY, you can also trade 10,000 of EEM and BAC at a whack without it changing price direction. Heck, you can do 30k size and without scaling on those 3 mentioned instruments and never notice your trades effecting the market.