Shipping is often referred to as a single alternative asset class that investment managers can use to diversify portfolios. That is true to a point, but treating shipping as a single homogeneous exposure misses much of the opportunity. There can be meaningful diversification benefits, and potentially alpha, from allocating deliberately across segments rather than lumping them into one bucket. Crude tankers and container liners in particular present greater diversification potential than most investors appreciate.
The listed maritime shipping equity universe is relatively small, at roughly $220 bn in market capitalisation, but it is spread across multiple segments. The most well-capitalised companies are found in container shipping (approximately $170 bn), with attractive opportunities also in tankers (roughly $40 bn) and dry bulk (roughly $12 bn), where periods of geopolitical tension and shifting trade patterns have historically shaped returns.
Correlated in bulk, decoupled at the edges
The correlation matrix below shows how segment-level equity returns have moved together over the past five years. As expected, the bulk sub-segments, major and minor dry bulk, crude and product tankers, are fairly correlated at around 0.5. Part of this reflects that these segments are ultimately tied to commodity flows and the broader industrial cycle, where China's demand has been a dominant driver over the past two decades. By contrast, the correlation between container liners and crude tankers sits at just 0.18, and container liners to product tankers is only marginally higher at 0.22.
| Major bulk | Minor bulk | Crude tanker | Product tanker | Container liners | Container feeders | |
|---|---|---|---|---|---|---|
| Major bulk | 1.00 | 0.54 | 0.50 | 0.49 | 0.34 | 0.66 |
| Minor bulk | 0.54 | 1.00 | 0.30 | 0.33 | 0.39 | 0.51 |
| Crude tanker | 0.50 | 0.30 | 1.00 | 0.78 | 0.18 | 0.48 |
| Product tanker | 0.49 | 0.33 | 0.78 | 1.00 | 0.22 | 0.50 |
| Container liners | 0.34 | 0.39 | 0.18 | 0.22 | 1.00 | 0.46 |
| Container feeders | 0.66 | 0.51 | 0.48 | 0.50 | 0.46 | 1.00 |
The crude and liner diversification angle
Looking more closely at the relationship between crude tankers and container liners highlights a concrete diversification angle. The rolling 90-day correlation between the two segments is clearly positive but never structurally tight, drifting between roughly 0.05 and 0.55 across the period, and only occasionally do they move together for sustained stretches. From an investment perspective, that creates real room to diversify risk within shipping while still maintaining sector exposure.
Rolling correlation between crude tankers and container liners
- 90-day rolling correlation
This is a strategy that has been leveraged by some of the most reputable shipowners over time through diversification of their fleets across segments. Owning both bulk and container exposure smooths the earnings profile through the cycle and gives management more room to redeploy capital toward whichever market is paying at any given moment. It is a less-obvious argument for scale in shipping. The point is not the cost side of the business, but the fact that different segments earn at different times.
Two factors to keep in mind
Shipping is ultimately tied to the underlying commodity and trade backdrop. Certain events, such as energy shocks or broader risk-off episodes in equity markets, tend to push correlations up across the board and move the whole sector together regardless of segment. When that happens, diversification within shipping offers less protection than the average five-year correlation would suggest.
Several segments have also been shaped by the same set of geopolitical events over the past five years, from Red Sea rerouting to the more recent disruptions in the oil complex. When the same headline is the marginal driver across several sub-segments at once, some of the excess return you would expect from combining lower-correlated pieces gets compressed. The regime can shift back, but it is worth noting when reading the current numbers.
Neither of these factors changes the underlying argument. A real diversification opportunity exists within shipping if investors allocate across segments deliberately rather than treating the sector as one exposure, and doing so gives access to a sector that has delivered impressive returns over the last year.
