The price of a share is only one price an investor encounters. There is also the cost of finding a counterparty and completing the trade. On October 27, 1986, London's Big Bang reforms changed the organization of the securities market, including the rules surrounding commissions, participation and the roles firms could perform.
The useful question is simple: Can changing the business of trading make a market more competitive without changing what the underlying companies are worth? Yes, these are different economic questions. Market design concerns how buyers and sellers meet; company value depends on the businesses and the claims being traded.
The change that happened on October 27
The Bank of England's March 1987 review explicitly dates completion of the Big Bang package to October 27, 1986. It describes a changed membership that brought in British and foreign banks and securities houses. HMRC's account identifies the movement toward electronic trading and the end of older restrictions on membership and business roles.
The reform changed the conditions under which firms competed to provide market services. Fixed commissions were removed, and the previous separation between brokers representing customers and dealers trading on their own account was relaxed. These changes concerned the structure of intermediation, rather than an announcement of profits by the companies whose shares were listed.
That distinction is important whenever a market reform receives a dramatic name. A new trading arrangement can be consequential without making every security a better investment. The relevant evidence must match the claim being made.
Why the cost of a trade matters
Someone comparing two investments may focus on the quoted buying price. But completing and later reversing a position can involve commissions and a difference between the price at which an intermediary buys and sells. Those transaction costs affect what a participant must gain before the activity produces a positive result.
Competition among intermediaries can put pressure on the cost and quality of those services. A firm seeking customers has a reason to consider the terms its rivals offer. Removing a common commission schedule changes one part of that contest; it does not eliminate every expense involved in executing a trade.
The Bank's early review reported evidence of increased competition, lower transaction costs and improved liquidity. That was an assessment of developments observed at the time, not a guarantee about every future trade or a percentage saving applicable to every investor. Preserving that qualification keeps the historical finding separate from a permanent promise.
Liquidity means being able to trade
In this context, liquidity concerns the ease of buying or selling a security without having to accept a large adverse movement in price. A market with more willing counterparties can be more useful to participants who need to adjust their holdings. It is not the same thing as a company having cash available to pay its bills.
The distinction helps explain how a trading reform can matter to a business indirectly. Investors considering a security may care about whether they can sell it again when their circumstances change. That consideration can influence their willingness to participate. It still does not establish that any particular company will receive cheaper funding after a rule change.
For a household holding investments through a fund or pension, market arrangements can sit several steps away from the visible account balance. The costs of intermediating trades may affect the operation of those vehicles, but the effect on a particular account requires evidence about its actual activity and charges.
More competition also changes the institutions
Opening participation and allowing broader business roles can increase the resources a firm can bring to the market. It can also create organizations carrying out activities that had previously been separated. The competitive question then extends beyond the number of firms: it includes their roles, incentives and relationships with customers.
A firm acting for a customer faces a different task from a firm trading for itself. When both activities occur within one organization, clear procedures and oversight matter to how those roles interact. That is a general consequence of combining functions, rather than an allegation about a particular participant in the 1986 market.
The Bank's review treated regulatory cooperation as an important part of the emerging framework. The historical story therefore includes both opening the market and adapting the arrangements surrounding it. Technology, competition and supervision were related parts of the change.
October 27 offers a practical way to read financial reform. Ask which cost or constraint changed, who can now compete, and what evidence shows about the resulting service. A better trading mechanism can be economically useful. It remains a different claim from predicting higher share prices or a guaranteed return for the people using it.