It’s that point of yr once more when many people have interns becoming a member of the desk. So, over the subsequent few weeks, we’ll replace our guides on buying and selling, exchange-traded funds (ETFs) and choices. Plan your Fridays accordingly!
As at all times, we’ll embody hyperlinks to further analysis for interns trying to take a deeper dive into any of the subjects talked about.
For those who’ve labored out there for years, we all know all of this. Simply benefit from the refresher — you by no means know when an intern may ask a query in regards to the fundamentals.
Markets assist match consumers and sellers in an environment friendly manner
All markets, even those you store in for groceries, have a reasonably easy underlying goal: to deliver collectively consumers and sellers. Doing commerce in a centralized manner permits customers to check costs and producers to promote to extra clients directly. Economically, it’s a win-win.
Inventory markets add one other dimension as additionally they present firms with entry to traders. Money from traders permits firms to spend money on their companies and, in the end, develop earnings, which in flip supplies revenue again to the traders.
The markets are an ecosystem
Whether or not centralized or not, markets work finest with a various ecosystem of members, every with their very own specialised function to play in shopping for, promoting and valuing shares.
Traders present capital to firms, which then present dividends and returns to traders. Banks assist traders worth shares, whereas exchanges permit merchants to supply liquidity and arbitrageurs to appropriate mispricings. This all occurs on the identical costs regardless of the completely different commerce indicators and lengths of time they maintain shares.
For instance, an arbitrageur may see ETFs dislocate from inventory values for a couple of seconds, however a mutual fund portfolio supervisor could resolve to purchase a inventory to carry for 2 years primarily based on anticipated development in gross sales.
Chart 1: The inventory market ecosystem
Itemizing exchanges deliver all members collectively
Itemizing exchanges play a central function in inventory markets, actually. They record firms, assist merchants purchase and promote their shares, and share costs with different traders and analysts.
Itemizing exchanges even have itemizing requirements, which work alongside the U.S. Securities and Trade Commision’s (SEC) guidelines that require corporates to share quarterly accounting statements and different disclosures. That makes inventory markets extra clear and comparatively safer for traders. That’s why pension and mutual funds typically solely spend money on so-called “listed” shares.
There are round 5,500 firms and over 3,000 ETFs which can be traded within the U.S.
The place a inventory is “listed” impacts what “tape” its costs and trades are reported on. There are historic causes for that. Previously, trades had been actually printed onto paper “ticker tape” from the placement the place trades had been occurring. In the present day, there are nonetheless three “tapes” that publish trades and costs:
- Tape A is for all NYSE listings (no matter what trade the commerce truly happens on).
- Tape C is for all Nasdaq listings (no matter the place trades happen).
- Tape B is for all different exchanges, together with the Cboe exchanges and NYSE Arca (which predominantly record ETFs) in addition to NYSE American (which usually lists small firms).
Chart 2: Variety of U.S. firms on every “tape”

Index suppliers use the first itemizing trade’s closing public sale to calculate the final “official” commerce of the day. That makes the closing public sale for the first trade vital for matching liquidity and minimizing volatility. It is also vital for mutual funds that use the near calculate unit costs used to speculate buyer money flows.
Though only some exchanges record shares, all exchanges can commerce shares, and all are required to be open to everybody. One other factor that each one exchanges do is to promote costs to everybody.
Public costs assist consumers discover sellers and commerce at the very best costs out there. In addition they assist non-traders worth portfolios and let portfolio managers purchase dips and promote peaks. Competitors for the very best costs additionally creates tighter spreads that cut back transaction prices for all traders (even those that don’t commerce on an trade).
That gives what economists name “optimistic externalities.” Everybody advantages – even those that aren’t buying and selling.
Issuers give us tickers to commerce and dividends to save lots of
Firms, additionally referred to as “issuers” as a result of they subject shares, are essential to public markets and to the U.S. financial system. With out issuers becoming a member of public markets, there could be no firms for the general public to spend money on, no dividends for traders, and fewer methods to hedge and commerce.
Traders then profit from dividends and capital features, that are generated primarily by earnings development.
Chart 3: Inventory costs align with earnings

The day of an preliminary public providing (IPO) is vital for a corporation, too. Elevating money can permit an organization to develop. Having a inventory that trades additionally makes it simpler to subject extra shares (in a “secondary” elevating) sooner or later. That makes it simpler to spend money on gear and staff – rising revenues and the financial system.
Apparently, IPO exercise rises and falls primarily based on a number of financial components. IPOs additionally characterize a possibility for traders to profit from the liquidity premium that public buying and selling provides to a inventory. On common, day-one returns for IPOs are optimistic.
Importantly, U.S. inventory markets aren’t the one place new firms can discover traders. Our listed markets compete with personal markets, OTC markets (previously together with pink-sheet and bulletin board shares) and worldwide inventory markets for listings.
That stated, the U.S. inventory market is engaging to issuers. It has the most important supply of fairness capital, stronger valuations, the bottom buying and selling prices and, arguably, probably the most liquidity on the earth.
Issuers want traders
With the intention to elevate capital, issuers want to draw traders. Lengthy-term traders are available in two essential flavors:
- Mutual funds and pension funds (additionally referred to as “institutional traders”) are the place an expert manages a portfolio for a gaggle of particular person traders.
- Retail traders (or “households” in Chart 4) can execute trades and handle their very own portfolios instantly from an app on their telephones.
Knowledge suggests they each have roughly the identical quantity of capital to speculate (roughly $20 trillion every).
Chart 4: Who owns shares (primarily based on year-end 2024 information)

All traders are attempting to maximise their funding returns. Many mutual funds will analysis shares to attempt to discover firms that may develop revenues the quickest, pay the very best dividends, have the very best revenue margins, or provide the very best worth (nevertheless you outline that).
These funds and the professionals managing them present an vital function in what we name “value discovery.” Their shopping for makes good firms’ costs go up, whereas firms with much less rosy outlooks see their costs fall as traders promote. It’s a part of what helps markets effectively allocate capital. Nonetheless, actively choosing shares that outperform can also be how portfolio managers attempt to beat the market.
Different portfolio managers run index funds. These attempt to purchase each inventory in an index, normally at market weight. These funds save prices, as they do much less analysis and far much less buying and selling. They’re additionally relying in the marketplace’s total effectivity to make sure the costs they pay will not be inefficient.
Knowledge evaluating returns of index and energetic funds suggests the market could be very environment friendly. Latest information additionally reveals that the property in index funds at the moment are bigger than these in actively managed mutual funds.
Retail traders additionally need to maximize funding returns, or no less than reduce losses. As app-based buying and selling and commission-free buying and selling has made it simpler for retail to commerce than ever earlier than, retail buying and selling has additionally grown. One factor the info reveals is that though retail commerce shares extra, they’re persistently web consumers of ETFs, a type of mutual fund that trades on trade.
Issuers and traders want banks and brokers
More often than not, issuers and traders want banks and brokers to assist them enter and exit the market.
Banks have many direct relationships with issuers and mutual funds. They typically lend to firms. In addition they analysis firms and execute trades for mutual funds, generally utilizing their very own various buying and selling techniques (ATSs), comparable to darkish swimming pools. So, they contribute to each capital formation and liquidity.
Forward of an IPO, brokers will canvass traders to evaluate curiosity, assist value and allocate shares within the IPO. The IPO is named a main market.
Then, as traders purchase and promote shares to vary their portfolio holdings in so-called “secondary” markets, they normally want brokers to “work” their orders over time.
Traders want shorter-term merchants to maintain markets environment friendly
There may be not at all times one other investor trying to promote when a brand new investor needs to purchase. That’s the place short-term merchants – from hedge funds and banks to market makers and arbitrageurs – assist.
Though every has completely different funding goals, all of them play a essential function in preserving markets environment friendly and liquidity low cost. Our estimates additionally counsel they make up the vast majority of buying and selling (Chart 5).
Chart 5: Traders have the vast majority of property; intermediaries do the vast majority of buying and selling

Market makers don’t maintain shares for lengthy, however their specialty is being each a purchaser and vendor on the identical time. Making a “two-sided market” in every inventory ensures traders can commerce no matter whether or not they wish to purchase or promote. In return, market makers hope to earn the unfold, or the distinction between the bid and the provide.
Arbitrageurs assist futures and choices observe their underlying asset costs very effectively. Our analysis reveals that ETFs commerce consistent with their portfolios’ web asset values even when the ETF doesn’t commerce. Thanks to classy statistical hedging methods, many ETFs are literally cheaper to commerce than their underlying shares.
Hedge funds, in distinction, have a tendency to carry lengthy and quick positions on the identical time. Their methods typically maintain comparable shares, generally referred to as pairs, effectively valued. That helps maintain markets extra environment friendly, including promoting to a purchaser of 1 inventory by shopping for a hedge from a vendor of one other inventory. Analysis even reveals that quick sellers assist maintain markets environment friendly by including sellers to overbought shares.
Market guidelines have advanced over time
Inventory markets have rallied and crashed a number of occasions in historical past. Typically, following bear markets, guidelines are modified to guard traders. That’s precisely what occurred after the most important bear market in U.S. historical past, which adopted the Nice Melancholy within the U.S., the place shares fell over 85% from their highs as unemployment reached 24.9%.
Within the decade that adopted the Nice Melancholy, U.S. markets noticed the introduction of quite a few new guidelines to guard traders:
- Securities Act of 1933: Established guidelines for IPOs in order that traders would have info on which to base their funding valuations.
- Banking Act of 1933 (also called the Glass-Steagall Act): Separated business banks that lent homebuyers cash and funding banking that traded shares and bonds. To this present day, insurance coverage on financial institution accounts (FDIC) and brokerage accounts (SIPC) is completely different, though Glass-Steagall was repealed, permitting immediately’s mega-banks to do inventory broking and banking for his or her clients.
- Trade Act of 1934: Established the Securities and Trade Fee (SEC) to manage inventory and choices markets and set exchanges as self-regulatory our bodies (SROs) accountable for policing their very own listed firms and buying and selling guidelines.
- Formation of NASD in 1938: The Nationwide Affiliation of Securities Sellers (NASD) regulated the buying and selling of shares that weren’t listed on exchanges. It has since turn out to be Nasdaq (buying and selling) and FINRA (dealer regulation).
- Funding Firm Act of 1940: Set all the principles that mutual funds (together with ETFs) have to observe, together with protected custody of property and limits on leverage.
Chart 6: Market rises and falls (log scale)

Establishing for fragmentation of liquidity and buying and selling
One other important regulatory change occurred in 1975 with the Securities Act Amendments. These guidelines arrange what we now name the Nationwide Market System (NMS). Maybe most significantly, brokerage fee charges had been deregulated by the SEC, a transfer that drew important criticism as Wall Road cried Might Day. Nonetheless, in a development that will play out once more over the next a long time, decrease prices led to rising quantity that has lengthy since made up for decrease charges.
Then, in 1994, Congress handed the Unlisted Buying and selling Privileges Act of 1994, which allowed any trade to commerce any ticker—no matter the place that inventory was listed. In the present day, there are 16 exchanges and greater than two dozen darkish swimming pools, all of which may commerce any listed U.S. inventory. There may be additionally an increase in “off-exchange” buying and selling, which incorporates darkish swimming pools, retail buying and selling, and bilateral buying and selling.
Though Instinet launched the primary darkish pool in 1986, Reg ATS didn’t set constant guidelines for darkish swimming pools to commerce in till 1999.
Chart 7: In the present day’s market is fragmented, with many venues in a position to commerce any shares they need

Market automation additionally began within the ‘70s
It most likely appears laborious for an intern to imagine, however as just lately because the Nineteen Nineties, most shares had been traded in individual, in “pits” or at “posts” on the ground of an trade, with every commerce written down on tiny items of paper that had been taken again to the workplace to be processed for patrons. The following day, interns would most likely be part of “runners,” delivering bodily inventory certificates from the vendor’s dealer to the client’s dealer.
Some flooring do nonetheless exist immediately, however the U.S. market began to automate again in 1971, an occasion that in the end created Nasdaq. Though Nasdaq’s first “information facilities” had tape drives, monochrome cathode tube screens, sideburns and plaid trousers. Quite a bit has modified since then.
Exhibit 1: A Nasdaq information heart in 1971, the yr the corporate’s digital trade started working

With most floor-based markets, all traders would see was a ticker tape of historic trades, actually a rolled-up piece of paper with typing on it, effectively after the trades had truly occurred. Even immediately, the trade refers informally to the report of all quotes and trades as “the tape.” You may even hear a dealer nonetheless say a commerce has “hit the tape,” which implies it’s now on the display screen and within the database.
Shifting from automated quotes to trades
In its first iteration, the Nationwide Affiliation of Securities Sellers (NASD, now FINRA) constructed a system for market makers in OTC (usually micro-cap) shares to electronically replace their bid/ask quotes. That turned the NASD Automated Quotations (therefore the acronym NASDAQ).
Exhibit 2: One of many early Bunker-Ramo pc terminals used to make and see quotes

Over time, as computer systems improved, extra information may very well be shared extra simply. This benefited traders and merchants who couldn’t essentially see what was occurring on different human buying and selling flooring.
The principle information innovation within the Eighties was the creation of a real-time “Stage 2” information feed. Greater than merely offering the very best bid and provide, Stage 2 confirmed all market maker quotes at completely different costs beneath the bid and above the provide. What’s now referred to as “depth.”
Exhibit 3: The quote montage from the Nasdaq Workstation II within the late Nineteen Nineties, exhibiting depth (Be aware costs are in fractions of a greenback; some bonds nonetheless commerce in fractions immediately)

Automating executions after the 1987 crash
One other large market crash occurred in 1987 when the S&P 500 fell greater than 20% in sooner or later. Again then, there have been no market-wide circuit breakers or different guardrails to gradual markets down and permit consumers to assemble.
Within the aftermath, it was found that many market makers had been unable or unwilling to commerce regardless that purchase costs may very well be seen on the screens. Shortly after, the method of matching trades was additionally automated, creating what we now name “actionable quotes.” Though of their early kinds:
- The Small Order Execution System (SOES) automated executions as much as a most of simply 1,000 shares to guard market makers from giant market actions.
- The SelectNet system allowed merchants to create locked-in trades—though it labored much more like electronic mail for buying and selling.
Decrease prices drive liquidity and exercise into the 2000s
Nonetheless, that set the scene for a market that appears extra like what we all know immediately – the place nearly all trades are executed electronically. And because the market adopted computerized buying and selling, vital new guidelines had been launched:
- 1997 – Order Dealing with (Manning) Guidelines: Now that clients may be part of the identical bid as market-makers, manning required brokers to place buyer orders first. That made it simpler for traders to commerce with one another and seize extra spreads.
- 2001 – Decimalization led to quotes being in cents, which we see immediately, not fractions, as we noticed above. That adopted fractional ticks lowering from eighths to sixteenths in 1997, all of which made unfold prices a lot smaller and market-making much less worthwhile.
- 2007 – Reg NMS mandated many issues we take without any consideration immediately: quotes which can be publicly out there and actionable, costs that may be consolidated in real-time to create an NBBO and an interconnected market that helps traders at all times commerce on markets with the very best costs.
Because of this, market-making turned extra automated, and buying and selling turned cheaper. From 1995 to 2005, markets noticed spreads decline 90%, and liquidity elevated tenfold. Apparently, this all occurred earlier than Reg NMS was carried out in 2007.
Chart 8: The affect of market-wide automation lower buying and selling prices and boosted liquidity

As a result of spreads are so tight, and trades are all reported electronically now, newer SEC guidelines have been centered on altering ticks as soon as extra, in addition to including extra information and smaller trades to public feeds.
Buying and selling on the velocity of sunshine
This all implies that over the previous 50 years, buying and selling has gone from human velocity to pc velocity to the velocity of sunshine. Though for any interns working in digital buying and selling, it could be vital to know that mild travels sooner in air than in optic fiber.
Computerized buying and selling has led to fewer handbook errors, sooner processing and cheaper buying and selling. It has additionally made buying and selling sooner. Quite a bit sooner.
In actuality, nearly all buying and selling in U.S. shares is completed in information facilities in New Jersey lately. On the velocity of sunshine, it takes trades about 0.0002 seconds, or lower than 0.2ms, to journey from one trade to a different. To place that in perspective, a human blink takes round 1 / 4 of a second (that’s 250 milliseconds).
All of that is to say that arbitrage occurs in a short time, and markets at the moment are very environment friendly.
Chart 9: Distances between buying and selling facilities on the velocity of sunshine

The place do public costs come from?
Within the U.S., a sequence of centralized computer systems, referred to as the SIPs, places all of the fragmented quotes again collectively.
The SIPs obtain the very best bid and provide from all of the exchanges for each inventory out there. It then kinds them to seek out which trade has the very best bid and which trade has the very best provide. Then it creates a single unified nationwide finest bid and provide (NBBO), which is made out there to all traders.
These are the “tapes” that we talked about earlier. It additionally lets traders know what the very best value is, and the place they should go to get it.
Chart 10: SIPs compile the NBBO primarily based on all of the exchanges’ quotes in a particular safety

Though, the key enchancment in spreads occurred over 20 years in the past (Chart 8), the market infrastructure has continued to evolve to maintain up with the modifications in computing energy. Previously 14 years, even the SIP has elevated its capability greater than 40-fold whereas on the identical time lowering the time it takes to calculate the very best value by greater than 99.6%.
Chart 11: The SIP has been in a position to deal with extra messages at a sooner price over time

Market construction helps everybody make investments and commerce higher
In the present day’s inventory markets are quick and sophisticated. However the excellent news is that there are many guidelines designed to make it look easy and shield traders.
That’s to not say they’re excellent. There are ongoing debates about issues like odd tons and tick sizes, retail buying and selling and quick promoting guidelines, in addition to competing concepts on the optimum solution to allocate the economics of value setting and buying and selling.
Total, although, our market construction helps make U.S. markets among the least expensive and most liquid to commerce in — and that’s good for traders and issuers.