A great deal these days depends on systems and platforms for trading. More to the point, conventional stock exchanges (however automated they have become) have significant competition from more recently formed trading systems and platforms.
We advise clients on the use it wants to make of a web site to promote its investments (or those of a third party). More complex issues arise where the web site is then used for simultaneous price quotation to selected investors: this may well be classed as a multilateral trading facility, which calls for its own form of licence from the FCA (distinct from mere brokerage).
Clearing and settlement are areas which are dominated by a handful of major brokerage firms. Our clients may well require advice on their relationship with "Model B clearers", whose terms are not always amenable to negotiation but which still have to be reviewed so that the clients understand the nature of their relationships.