Slippage/Front-running in Bulk deals

I had seen an article about slippage happening during bulk deals -

One of the deals highlighted in that article was of Kotak Mahindra Bank on June 2nd, 2020. Given that it was already known a day before that the deal was going to happen (refer to the tweets below), weren’t some slippage bound to happen in such case?

Also, as that particular transaction happened via block deals (CSV) instead of bulk deals, weren’t slippages prevented as block deal don’t allow any kind of partial order matching and orders expire within 90 seconds if they remain unfilled (as mentioned in a BSE FAQ about block deals)?


a similar surge seen in bpcl as well today. a block deal yesterday happened as part of its disinvestment

Block deals are ok I think, slippages are with bulk deals and both are different. Bulk deals happen on normal order matching system where as block deals on separate window where others won’t have access but with price controls.


why, despite the deal being a block deal as explained here, is visible on the chart?

As per the BSE’s FAQ about Block deals, some data from block deals does show up in charts/marketwatch -

21. Whether block deal is used in the calculation market picture data?
A. Block deal is considered for displaying day high, day low, total traded quantity, value and number of trades. However, block deal transactions executed in scrip are not considered for updating of LTP, opening price & closing price.

This block deal likely happened via NSE as the volume being shown is very high (around 8.68 crore shares were to be sold via this block deal) -

Upon checking the chart for Kotak Mahindra Bank, 2nd June 2020 also seems to reflect the volume of the block deal that I mentioned above (that deal happened on BSE, around 5.6 crore shares were sold via it) -