I currently have five FTSE 350 investment trusts inside my ISA and Self-Invested Personal Pension (SIPP). One of these is a new holding — 3i Group — initiated a few weeks ago while Pershing Square has risen 12% in the past year.

The other three, however, have been on fire. Let’s take a look at why, as well as a sixth one I’ve currently got my eye on.

Powerful themes

The trio I’m referring to are Scottish Mortgage Investment Trust (LSE:SMT), BlackRock World Mining Trust, and Pacific Horizon Investment Trust. The first is in the FTSE 100 while the other two are from the FTSE 250.

Here’s how they have performed in the past year (excluding dividends):

• Scottish Mortgage: +45.4%
• BlackRock World Mining: +109.2%
• Pacific Horizon: +92.5%

Each has benefitted from powerful individual investing themes. Scottish Mortgage has seen the value of its SpaceX holding skyrocket higher. In fact, SpaceX could soon become the largest IPO ever.

I’ve had to be patient with this investment. Three years ago, the growth trust traded at a massive discount to its underlying net asset value (NAV) because the market was wary about private holdings like Stripe, SpaceX and ByteDance.

While I do have some concerns about SpaceX’s extreme valuation, I remain bullish on Scottish Mortgage’s wider unlisted portfolio, which now includes Claude maker Anthropic and Revolut. I reckon the stock’s worth considering.

As for BlackRock World Mining, it has surged from its exposure to gold and silver miners. Even after a recent pullback, these precious metals are up about 44% and 158%, respectively, in the past 12 months.

Additionally, the trust has a sizeable weighting towards copper, which itself has increased 38% in value in the last year. Demand for the red metal is accelerating while supply remains constrained.

Accelerating hyperscaler spending on AI infrastructure, alongside electrification, grid expansion and the broader energy transition, is driving demand for both power and materials. Copper sits at the centre of this theme, given its critical role in electrification and power intensive infrastructure.
BlackRock World Mining.

The risk here is a sharp fall in the price of gold, which makes up around a third of the portfolio. This isn’t one I’m looking to add to right now, despite the 2.5% dividend yield on offer.

Finally, Pacific Horizon has benefitted from top holdings Taiwan Semiconductor (TSMC) and Samsung Electronics. These chipmakers have exploded higher due to their central role in the global AI infrastructure buildout.

A slump in these names is a risk to performance, though with Pacific Horizon trading at a 9.3% discount to NAV, it’s worth a closer look.

The sixth trust

Speaking of AI, I’m considering buying shares in Manchester & London Investment Trust. This one has gone all-in on AI hardware, with a portfolio packed full of chipmakers (Nvidia, AMD and Micron), semiconductor equipment stocks, energy providers, and data centre cooling firms.

Of course, there’s high sector concentration risk here, with Nvidia making up almost 25% of the portfolio itself. However, the trust has generated a 17% annualised return (with dividends reinvested) since 2015, and is offering a 3.7% dividend yield.

Better still, it’s trading at a 18.7% discount to NAV. It therefore offers a discounted way to get broad exposure to the AI buildout, which could reach a cumulative $7trn by 2030.