Direct Answer

The Dow Jones Transportation Average is a price-weighted index of 20 U.S. transportation-sector companies including airlines, railroads, trucking firms, and logistics providers, maintained by S&P Dow Jones Indices. It is one of the oldest U.S. market indicators still in active use and plays a central role in Dow Theory analysis of market trends.

What the Dow Jones Transportation Average measures and why it exists

The Dow Jones Transportation Average began as the Dow Jones Railroad Average, created in the late nineteenth century by Charles Dow and Edward Jones as part of an effort to summarize the condition of American commerce through the stocks most closely tied to the movement of goods. Railroads were the dominant form of long-distance freight transport at the time, making railroad stocks a reasonable proxy for the health of the broader industrial economy.

As the U.S. transportation industry evolved, the index evolved with it. Airlines, trucking companies, and logistics providers joined the list over time, and in 1970 the name was changed to the Dow Jones Transportation Average to reflect the expanded scope. The 20-company structure has remained broadly stable since that transition, though the specific constituents have changed as the industry has changed.

Today the index serves two distinct analytical purposes. First, it is a sector-specific performance measure for investors who want a quick read on how transportation companies are performing relative to the broader market. Second, it is a central input to Dow Theory, the framework for market trend analysis that Charles Dow's writings inspired. Dow theorists watch whether the Transportation Average and the Dow Jones Industrial Average are moving in the same direction, since divergence between the two averages is interpreted as a potential signal about the strength or sustainability of a market trend.

Provider and governance

S&P Dow Jones Indices maintains the Dow Jones Transportation Average and publishes the methodology document governing it. An index committee reviews constituent eligibility and makes decisions about additions and removals. Unlike rules-based indexes where constituents change automatically when a company meets or fails published criteria, the Dow Jones Transportation Average requires committee approval for any constituent change. This discretionary oversight is a distinctive feature of all the Dow Jones averages.

The committee considers whether a current member still represents the transportation sector adequately, whether better candidates exist, and whether any recent corporate action (such as a merger or significant business restructuring) has changed a constituent's character. Announcements of changes are made in advance so market participants can prepare.

S&P Dow Jones Indices licenses data rights to fund managers, data vendors, and financial product issuers. The current constituent list and weights are available through licensed data feeds rather than through Swoopr.

Eligible universe: sector, exchange, and domicile

The eligible universe for the Dow Jones Transportation Average is U.S.-listed companies in the transportation sector. The methodology defines transportation to include airlines, railroads, trucking, air freight, sea freight, and logistics. The committee may include companies from adjacent industries where their business is substantially transportation-related.

Companies must be U.S.-incorporated or have their primary listing on a U.S. exchange. Foreign-domiciled companies are generally not eligible. The index has a fixed constituent count of 20 companies, which means each addition must be accompanied by a removal. The committee selects constituents to ensure the index represents the breadth of the U.S. transportation industry across its major subsectors.

There is no explicit market capitalization minimum published in the same way that float-weighted indexes typically publish size thresholds, but in practice the 20-slot constraint means the committee selects among the most significant and representative companies in the sector rather than smaller or obscure names.

Weighting method: price-weighting

The Dow Jones Transportation Average is price-weighted, the same method used by the Dow Jones Industrial Average. In a price-weighted index, a stock's contribution to the index level is proportional to its share price rather than to its total market capitalization or float-adjusted market cap. A company whose shares trade at a higher price has a larger weight in the index regardless of how many shares are outstanding or what the company's total market value is.

The practical consequence is that a high-priced stock can dominate the index even if a lower-priced competitor is a far larger company by market capitalization. This is a known distortion relative to market-cap-weighted indexes, which are generally considered more theoretically sound from a portfolio weighting perspective. Price-weighting is retained in the Dow Jones averages for historical continuity: changing the method would break the long data series that makes these averages historically meaningful.

A divisor adjusts the index level whenever a constituent change or a stock split would otherwise cause an artificial discontinuity. When a stock splits, for example, the divisor is reduced so that the index level the day after the split equals the level the day before, net of genuine price movements. The divisor ensures that only real changes in the prices of the constituent stocks drive the index level, not mechanical events.

Rebalance and reconstitution schedule

The Dow Jones Transportation Average has no fixed annual reconstitution date. Constituent reviews occur on an as-needed basis, triggered by corporate events (mergers, bankruptcies, delistings) or by the committee's assessment that a current member no longer best represents the transportation sector.

Between constituent changes, weights shift passively as share prices move. There is no periodic rebalancing that resets weights to a target: once a company joins, its weight relative to others rises when its price rises and falls when its price falls, until the next constituent change resets the composition. This makes the index's sector exposure over time a function of how transportation stock prices move relative to each other rather than of any deliberate weighting decision between reviews.

How investors use the Dow Jones Transportation Average

Transportation stocks are sensitive to economic activity because their revenues depend on the volume of goods and people moving through the economy. When businesses are expanding, freight volumes rise and airline traffic grows; when businesses pull back, the reverse happens. For this reason, the Dow Jones Transportation Average is watched as an economic leading indicator by analysts who believe transportation company performance foreshadows broader economic shifts.

The most formalized use of this reasoning is Dow Theory. Dow theorists look for confirmation between the Industrial Average and the Transportation Average: if the Industrial Average reaches a new high but the Transportation Average does not, the divergence raises a question about whether the broader economy supports the industrial sector's gains. Conversely, when both averages reach new highs together, the theory treats this as confirmation that a primary bull trend is intact.

Sector investors use the Transportation Average as a benchmark for active transportation funds and ETFs. Index fund managers may license it as a tracking target, giving investors a ready-made vehicle for gaining transportation sector exposure without selecting individual stocks.

Macro analysts also watch the average as a real-time window into fuel cost sensitivity. Transportation companies have high exposure to energy prices, particularly airlines and trucking firms. Moves in the Transportation Average that diverge from general market trends sometimes reflect changing oil price expectations more than changes in economic activity.

Comparison with similar indexes

Dow Jones Transportation Average vs. Dow Jones Industrial Average: Both are price-weighted indexes maintained by S&P Dow Jones Indices, and both use a divisor to handle corporate actions. The Industrial Average holds 30 large U.S. companies across many sectors, while the Transportation Average holds 20 companies exclusively in transportation. The two are compared in Dow Theory analysis rather than treated as substitutes for each other.

Dow Jones Transportation Average vs. S&P 500 Transportation sector: The S&P 500 Transportation sector holds all transportation-classified companies within the S&P 500, weighted by float-adjusted market cap. It covers only large-cap companies already in the S&P 500 universe and excludes mid-cap and smaller transportation names. The Dow Jones Transportation Average's 20-company, price-weighted structure means the two measures can behave differently even in the same market environment.

Dow Jones Transportation Average vs. NYSE Arca Transportation Index: The NYSE Arca Transportation Index offers another measure of U.S. transportation stocks and uses a modified market-cap weighting. It covers a broader set of transportation names than the 20-company Dow Jones average and is used as the underlying for exchange-traded products that target transportation sector exposure.

Frequently Asked Questions

What companies are in the Dow Jones Transportation Average?

The Dow Jones Transportation Average holds 20 U.S. transportation-sector companies drawn from airlines, railroads, trucking firms, air freight carriers, and logistics businesses. S&P Dow Jones Indices publishes and maintains the constituent list. Swoopr does not republish it, because index providers license constituent data and Swoopr holds no such licence.

Why is the Dow Jones Transportation Average price-weighted?

The price-weighting method dates to the index's origins in the late nineteenth century, when computing resources and float data were not available to support more sophisticated weighting schemes. A higher-priced stock contributes more to the index level regardless of the company's total market capitalization. The method has been retained for historical continuity. A divisor is adjusted whenever a constituent change or stock split would otherwise distort the series.

Who maintains the Dow Jones Transportation Average?

S&P Dow Jones Indices maintains the Dow Jones Transportation Average. An index committee reviews constituent eligibility and approves additions and removals. Constituent changes require committee approval rather than happening automatically when a company meets or fails published criteria.

What is Dow Theory and how does it use the Transportation Average?

Dow Theory is a framework for interpreting market trends developed from the writings of Charles Dow in the late nineteenth and early twentieth centuries. The theory holds that a trend in the Dow Jones Industrial Average is more likely to be sustained when the Dow Jones Transportation Average moves in the same direction, on the reasoning that goods being manufactured must eventually be shipped. When the two averages diverge, some analysts interpret this as a warning that the primary trend may be weakening.

How does the Dow Jones Transportation Average differ from the S&P 500 Transportation sector?

The Dow Jones Transportation Average holds 20 price-weighted companies selected by a committee from across the transportation industry. The S&P 500 Transportation sector holds the transportation companies within the S&P 500, weighted by float-adjusted market capitalization. The S&P 500 version covers only large-cap companies already in the S&P 500 and uses a different weighting method, so the two measures can behave differently even when describing the same underlying industry.

How often are Dow Jones Transportation Average constituents changed?

The Dow Jones Transportation Average has no fixed reconstitution schedule. The index committee at S&P Dow Jones Indices reviews constituents as needed and may add or remove a company when a current member no longer adequately represents the transportation sector or when a superior candidate exists. Changes have historically been infrequent; the list tends to be stable for extended periods.

References

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