These were the worst-performing ASX 200 shares in October

These ASX 200 shares were sold off in October…

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

It was a month to remember for the S&P/ASX 200 Index (ASX: XJO) in October. The benchmark index charged an impressive 6% higher during the month.

Unfortunately, not all ASX 200 shares managed to climb with the market and some even recorded sizeable declines. Here's why these were the worst performers on the index last month:

A young male investor wearing a white business shirt screams in frustration with his hands grasping his hair after ASX 200 shares fell rapidly today and appear to be heading into a stock market crash

Image source: Getty Images

St Barbara Ltd (ASX: SBM)

The St Barbara share price was the worst performer on the ASX 200 in October with a 31.1% decline. Investors were selling this gold miner's shares following the release of the company's first quarter update. That update revealed weaker than expected production and higher costs, which led to St Barbara downgrading its full year production guidance and increasing its all-in sustaining cost guidance.

Brainchip Holdings Ltd (ASX: BRN)

The Brainchip share price was sold off in October and dropped a sizeable 25.3%. The majority of this decline came after the semiconductor company released a quarterly update which revealed cash receipts in line with what a café would generate. Yet Brainchip had a market capitalisation of $1.5 billion at the time. No wonder short sellers are targeting the company!

Megaport Ltd (ASX: MP1)

The Megaport share price wasn't far behind with a 21.8% decline last month. This was driven by the release of a first quarter update which was slightly below expectations on the top line. However, the real damage was done by the company's higher capex guidance, which is impacting Megaport's free cash flow breakeven goals.

Medibank Private Ltd (ASX: MPL)

The Medibank share price was out of form and sank 19% during the month. Investors were selling this private health insurer's shares after the company was hit by a cyberattack. Medibank estimates that its half year earnings will be impacted by $25 million to $35 million pre-tax. However, this doesn't include costs relating to potential remediation, regulatory, or litigation-related costs. Nor does it cover the brand damage and potential customer churn.

Motley Fool contributor James Mickleboro has no position in any of the stocks mentioned. The Motley Fool Australia's parent company Motley Fool Holdings Inc. has positions in and has recommended MEGAPORT FPO. The Motley Fool Australia has recommended MEGAPORT FPO. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Scott Phillips.

More on Share Fallers

Stressed businessman sits in panic amid digital stock market financial background.
Share Fallers

Why Megaport, Lendlease and JB Hi-Fi shares all crashed 14% to 15% this week

ASX investors punished Lendlease, Megaport, and JB Hi-Fi this week. But why?

Read more »

Woman checking out new laptops.
Consumer Staples & Discretionary Shares

Down 14% today: Are JB Hi-Fi shares now a bargain-bin buy?

Could JB's plunge mean a bargain buy?

Read more »

A man sitting at his desktop computer leans forward onto his elbows and yawns while he rubs his eyes as though he is very tired.
Share Fallers

Why did DroneShield shares crash 30% in July to new one-year lows?

DroneShield shares got smashed in July. But why.

Read more »

Man with his head on his head with a red declining arrow and A worried man holds his head and look at his computer as the Megaport share price crashes today
Share Fallers

Down 43%! What on earth happened with Liontown shares in July?

Investors pummelled Liontown shares in July. Time to buy?

Read more »

A bored woman looking at her computer, it's bad news.
Share Fallers

These were the worst-performing ASX 200 shares in July

These shares had a tough time in July. Let's find out why.

Read more »

A man dressed in a business suit freefalls from a rocky cliff with a grey sky background.
Share Fallers

Why these 3 ASX 200 stocks are crashing in this week's surging market

Investors sent these three ASX 200 shares tumbling 15% to 18% in this week’s rising market. But why?

Read more »

A man holds his head in his hands after seeing bad news on his laptop screen.
Share Fallers

3 ASX shares down at least 50% in FY26

Let's see why these shares were sold off during the last financial year.

Read more »

Side-on view of a devastated male investor laying his head on his laptop keyboard
ASX Share Market News

5 biggest losers on the ASX 200 in FY26

The worst performers include 2 sector leaders, and all 5 stocks more than halved in value.

Read more »