Why the SXX share price dip makes me want to buy more

Sirius Minerals plc (LON: SXX) shares have slumped. Is that a sign to sell, sell, sell or buy, buy, buy?

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

The Sirius Minerals (LSE: SXX) share price has dipped again, losing 40% in a little less than three months.

But the only thing I find surprising is that people are surprised by it. When I bought Sirius shares, the one thing I was pretty much certain of was that I’d be facing a volatile share price ride.

Can you think of any resource-based company that has had a smooth ride in its net-spending development phase? I can’t.

I expect Sirius shares to spike when news is good, drop when it’s less good, and probably wander slowly downward when there’s no news at all. This time, it’s been the revelation of increased development cost estimates that’s done the damage.

How much more?

The bulk of the share price dip came in September, when the company updated its estimate of the capital needed to get its potash mining operation to the first stage of production. The new figure comes in at between $3.4bn and $3.6bn, and that’s $400m to $600m more than earlier predictions.

Let me pose another question. How many major engineering/infrastructure development projects of this scale can you think of that have ever come in on budget? I’m sure some do, but I can’t put my finger on one right now. In fact, I’ve seen suggestions that between 80% and 90% of development projects come in over budget, and in my 30-year software development career, just about everything I’ve ever worked on took longer and cost more than expected.

Really no surprise

There will always be unexpected costs, and humans are notoriously bad at accounting for them, even when they know they’re likely to happen. Then there’s always pressure to keep cost estimates as low as possible — even when there’s no explicit pressure, there’s an innate human tendency to err on the optimistic side.

I’ve always expected surprises from Sirius Minerals as its development progresses, but the one thing I’m absolutely not surprised by is that its cost estimate has been lifted. And I say that even though I’m convinced that Sirius has done, and is doing, a much better job in its forecasts than is typical for major engineering projects.

I’d go as far as to suggest that anyone who thinks total cost estimates at such an early stage in a project can really be anything more than reasonably well-informed guesses should, well, perhaps reconsider their investment strategy.

What do we do?

I expect to see Sirius shares continuing on a jittery path over the next few months, as the company seeks to finalise its funding some time during the first quarter of 2019. In theory, we’re heading into a make-or-break period, as the securing of funds should see Sirius financially sound right through to production. But if it can’t get the cash, we can’t be sure whether it will even be able to survive beyond 2019.

But with so much at stake, I really can’t see major investors letting such a long-term opportunity slip through their fingers.

I reckon that means we’re now in a new buying opportunity, and it’s making a Sirius top-up look increasingly attractive as I’m considering what to do with dividend cash that has built up in my SIPP.

Alan Oscroft owns shares of Sirius Minerals. The Motley Fool UK has no position in any of the shares mentioned. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

The Mall in Westminster, leading to Buckingham Palace
Investing Articles

2 investment trusts from the London Stock Exchange to consider in 2026

Investment trusts have the potential to drive lucrative returns for UK investors. Here are two our writer is bullish on…

Read more »

British bank notes and coins
Investing Articles

Here’s a £30-a-week plan to generate passive income!

Putting a passive income plan into action need not take a large amount of resources. Christopher Ruane explains how it…

Read more »

Close-up of British bank notes
Investing Articles

Want a second income? Here’s how a spare £3k today could earn £3k annually in years to come!

How big can a second income built around a portfolio of dividend shares potentially be? Christopher Ruane explains some of…

Read more »

Close-up of British bank notes
Investing Articles

£20,000 for a Stocks and Shares ISA? Here’s how to try and turn it into a monthly passive income of £493

Hundreds of pounds in passive income a month from a £20k Stocks and Shares ISA? Here's how that might work…

Read more »

Snowing on Jubilee Gardens in London at dusk
Investing Articles

£5,000 put into Nvidia stock last Christmas is already worth this much!

A year ago, Nvidia stock was already riding high -- but it's gained value since. Our writer explores why and…

Read more »

Investing Articles

Are Tesco shares easy money heading into 2026?

The supermarket industry is known for low margins and intense competition. But analysts are bullish on Tesco shares – and…

Read more »

Smiling black woman showing e-ticket on smartphone to white male attendant at airport
Investing Articles

Can this airline stock beat the FTSE 100 again in 2026?

After outperforming the FTSE 100 in 2025, International Consolidated Airlines Group has a promising plan to make its business more…

Read more »

Investing Articles

1 Stocks and Shares ISA mistake that will make me a better investor in 2026

All investors make mistakes. The best ones learn from them. That’s Stephen Wright’s plan to maximise returns from his Stocks…

Read more »