Stock market tension’s growing, with AI stocks slumping as worries over a new tech bubble increase. Yet the FTSE 100 continues its march towards new record highs — as I type, it’s up roughly 2% over the past trading week.

Yet this isn’t the time for investors to get complacent. If the AI bubble does burst and a full-on crash happens, the FTSE would likely also plunge into the red. It’s why UK share investors need to get ready for a ‘worst case scenario’.

Having an action plan cannot only limit the carnage amid a stock market crash, it can improve investors’ chances of making excellent long-term returns.

With this in mind, which FTSE 100 shares should individuals consider if the market plummets? The history books suggest Reckitt (LSE:RKT) will be a top performer.

A defensive icon?

Reckitt’s one of the UK stock market’s biggest consumer goods manufacturers. In total, it has 11 so-called Powerbrands across the ultra-defensive health and hygiene markets. Examples include Nurofen painkillers, Dettol disinfectant, and Finish dishwasher tablets.

The colossal brand power of its essential everyday products gives it predictable revenues and cash flows across the economic cycle. So does the FTSE firm’s enormous regional wingspan protect earnings from localised pressures? Well, Reckitt sells an incredible 30m products every day across more than 80 countries.

This resilience goes a long way to explaining its outperformance during stock market crises. During the 2008 financial crisis, the FTSE 100 fell roughly 31%. However, Reckitt’s shares fell by ‘just’ 12%.

Reckitt repeated the trick again during pandemic-struck 2020 too. While the FTSE dropped 14%, Reckitt’s share price actually rose 7%, though its performance was boosted by higher-than-usual demand for hygiene products.

The question is, could Reckitt continue to outperform if the market slumps in 2026?

Mixed bag

I think so, even though latest trading news in October was a mixed bag. Then Reckitt announced Q3 like-for-like sales growth of 3.2%, the company flagging “good underlying performance despite a challenging consumer environment“.

But this was below forecast and caused the firm to cut growth estimates (to 3.5%-4.5%, from 4%-5%). Manufacturing problems at Lysol and slowing vitamin sales in China were flagged as the main culprits.

Yet broadly speaking, Reckitt’s overall performance remains strong. And it perfectly illustrates the strength of the company’s business model. Volumes are under pressure, but robust brand power means revenues and earnings keep rising.

Reckitt’s share price has risen 26% over the last six months. Personally, I’m expecting it to become more resilient following restructuring to double-down on its Powerbrands.

focusing on areas where Reckitt has market leadership should help drive better sales growth going forward… This collection of core brands has a history of outperformance and should be able to attract higher margins.

Hargreaves Lansdown

What could go wrong?

That said, Reckitt shares aren’t cheap right now. Its forward price-to-earnings (P/E) ratio sits around 18 times, which could cause it to fall if those Lysol production issues drag on.

Yet on balance, I believe it’s a share investors should consider. Strong sales, and a canny ability to pass on rising costs to consumers, means it could outperform again if the broader stock market crashes.

Should you invest £5,000 in Reckitt Benckiser Group Plc right now?

When investing expert Mark Rogers and his team have a stock tip, it can pay to listen. After all, the flagship Twelfth Magpie Share Advisor newsletter he has run for nearly a decade has provided thousands of paying members with top stock recommendations from the UK and US markets.

And right now, Mark thinks there are 6 standout stocks that investors should consider buying. Want to see if Reckitt Benckiser Group Plc made the list?

Royston Wild does not hold any positions in the companies mentioned.