Now, some people have mentioned the vacuum effect. This is not what I will call a stop run. The vacuum effect is real though. Vacuum occurs when aggressive bulls/bears take out a position and the market doesn't move in their favor. The liquidity providers pull the market above/below them to trigger their near to market stops. This does happen. It happens primarily in the overnight. It is often triggered by a resting order imbalance.

One explanation from traditional technical analysis for stop runs is that large traders need to test the market at the extents before placing their large orders. This makes some sense. Before you sell a ton of contracts, it might pay to bid the market up so make sure that nobody else is interested in buying. After you get the confirmation that no one wants to buy, you have confidence to sell. This makes sense but it could also be explained that higher uncertainty is a characteristic of tops/bottoms and so range testing is just a product of that.

Can you expand on this vacuum effect please? I dont understand what you mean.



In what form does this confirmation come? Aggressive selling or passive buying? What are the signs that this activity is afoot?

Regarding vacuum effect, you have to have software where you can view the actual orders to see it. I have seen it in the ES but only overnight or when liquidity is lower. The effect at least very clearly looks like a manipulation. An example of the vacuum is you get strong selling at new lows and then the orders are pulled above the market very fast. The key to a vacuum is that either no orders or very few orders transact-- hence the trap. An explanation is that a large liquidity provider, took the other side of the trade and simply pulls the resting orders above the market to trigger the aggressive sellers stop orders. The pattern is aggressive selling at new lows, resting orders pulled above, and few/no transactions. Vacuum effect is not going to be more then a say a few to several ticks but can mark swing lows or highs.

It happens too fast generally to take advantage of it from a discretionary phase. However, the signaling is typically a large order book imbalance. So the conditions would be 1. A lower liquidity market, 2. Aggressive selling at lows, 3. A large buy side imbalance shows, 4. Orders above the sellers are pulled and either only a few contracts trade or no contracts trade. For it to be a true vacuum, I think you need #4 or else it could just be explained by the order book imbalance. I have seen it in the ES in the overnights. I do not think it is likely to occur during RTH.

I'm not sure I'd consider it a stop run. Maybe a trap but sure it could be a form of stop run but not the classical high volume stop run. I think the key to measuring a stop run is to see how fast the orders hit the level. If they are using stop orders then after you get a single trade then all the stop orders should trigger unless they are using volume trigger stops or other advanced order types. If the buying/selling comes in later then it wasn't a stop order. If you track the number of orders that hit a level first then you can get an idea of the maximum number of stops held at a level. If only a few orders hit a level and nothing triggers then you know the market is trading very efficiently because there aren't any retail traders. Most of the activity now is professional.

I suggest you invest some time reading the CME block trade rules - and esp the rules regarding trade disclosure.
In the end you will find that you have 2 components in your reconstructed tape: a) A realtime component that
consists of the small change and trades that were disclosed when they were closed and b) trades that max out
diclosure times.

Compared with ancient times the b) part of your reconstructed tape is delayed data.

I'm interested in CL so I went to the CME Block Trades webpage and searched for the CLV17 trades for yesterday 9/12/17 and copied the list into excel and did a little statistical analysis. There were 28 trades yesterday with a total volume of 11,422 contracts. Average volume = 407.9, Stdev = 413.9, Median = 275. There were 4 trades of at least 1000 contracts. Total volume, from my daily chart (data provided by CQG) for 9/12/17 was 498,903 contracts. The first block trade occurred at 0715 CT and the last occurred at 1412 CT. The source for all the trades was listed as "CPC" which, I'll wager, means ClearPort. So if my figures are correct, block trading was about 2.3% of all "transparent" trading.

One of the reasons I came to the futures market was because I thought there was greater transparency and the absence of dark pools, as well as better directional volume information; but I must admit my increased awareness of block trading and clearport has somewhat diminished my enthusiasm for CME products.

Thanks Choke 35 for enlightening me.

2.3% is negligible ...

I called CQG and asked if and when ClearPort trades are reported on the tape. The response was not encouraging.

The "settlements" get reported by CQG at the end of the day.