Trading Corporation of Pakistan does step in on occasions but its main task is to intervene in the market where shortages or excesses threaten orderly market conditions in essential commodities. The most successful experience of deregulation has taken place in the telecom sector.
Liquidity regulation has caused some repricing in the market, with somewhat lower inventories, particularly of less liquid securities, as a result. So aspects of the regulation have increased the cost and you would expect that to increase the price of providing the service. In this case, that would be a wider bid-ask spread. In turn, you would expect that to lower turnover.