One cannot push high volumes without affecting price, and the skewness would show up in the price as well as volume, manipulation in a way of insider information is possible , but cornering as in old days are distant possibilty now a days even in stocks, well one may say that there are some stocks which are operator driven , but then index manipulation, its nearly impossible because there are so many forces playing there.One wouldn't sit idle if one manipulates, be it HFT or algo or otherwise.
If FII wanted to go short in the index and go unnoticed, they buy put and short call. this synthetic short wont show up on the net transaction activity as option data will show zero activity. Its not feasible to know either when it is being manipulated. Lets face it...they are very smart people who have to get away with their activity under the scanner of authorities who keep very careful eye on their accounts.
The big players have the problem of pushing big volume. They can wait for charts to show bottom formations. They are the reason the bottom formations occur on our charts....!
Thats why objective of trading is to stay on the side on smart money...!