Intraday auctions

[SanMiguel]

When are intraday auctions likely to occur.
I wa strading a small cap today that ran to 25% but at regular intervals during the run up, IG would prevent any trades from being actioned on the stock.
The reason they gave was this:

Occasionally a share can go into an intra-day auction. This is when the exchange temporally suspends trading on a particular stock during market hours. At this time we will not be able to trade this stock so we set the share to 'Market Closed'. This normally only lasts for a minute or two but it can last longer, and it can happened a number of times in a single day.

Why the hell would a share go into auction in the middle of the trading day?

 

[barjon]

http://www.trade2win.com/boards/intraday-data/80620-intra-day-auctions-lse.html#post990164

 

[SanMiguel]

http://www.trade2win.com/boards/intraday-data/80620-intra-day-auctions-lse.html#post990164

What's the point? Is it the equivalent of a limit up, limit down cooling off system?

 

[MrGecko]

I thought I heard that IG kept markets open in these circumstances and hedged in Chi-X or whatever, and that is one of the reasons they are now larger (mkt. cap) than the LSE..??