RE: something for the weekend...26 Jun 2020 19:19
Jimzi - how about this from LSE rules-
Where a market maker is approached by a member firm, other than a market maker in that security, it shall actively offer to buy and sell at its displayed price and in any size up to that displayed in its firm quote.4203 - (so do we know the EMS at the time of the trade on the 5th June? I don’t but it is possible)
Where a market maker, who has not caused a back or a choice under rule 4204, is approached by another market maker in the same security, the market maker shall effect a trade with the enquiring market maker at the approached market maker’s displayed price in up to the Exchange market size where the enquiring market maker; wishes to sell the security, and it is displaying on the trading system a lower bid price and a lower offer price than the market maker approached; or 4203.2 wishes to buy the security, and it is displaying on the trading system a higher bid price and a higher offer price than the market maker approached
A market maker which actively causes a back or choice shall be obliged to deal at its displayed price and in its displayed size upon enquiry from any member firm.
Guidance to Rule: Where a market maker creates a back or choice by automatically opening at its overnight price, and the opening price does not reflect the fair value for the security, it is deemed to have actively caused a back or choice. Except where a market maker is ‘left behind’ a moving market, a market maker is not deemed to have actively created a back or choice by virtue of another market maker changing its quote. Where a market maker that creates a back or a choice has already been approached under rule 4204, its obligations under 4205 shall begin with market makers with whom it had not already dealt under rule4204.(Amended N09/17 –effective 3 January 2018)
*** 4206 Where a market maker is approached under rule 4205, the approached market maker must effect a trade in accordance with rule 4203 and, if it deals in less than the challenged size, immediately change its firm quote such that it is no longer contributing to the back or a choice..
hope that helps regards DJ