The S&P/ASX 200 Index (ASX: XJO) gained 2.2% in July, but not all ASX 200 stocks joined in the run higher.

Below, we look at three companies that may have delighted short sellers over the month but were best avoided by buy-and-hold investors.

What pulled these three ASX 200 stocks down in September?

We'll start with Spark New Zealand Ltd (ASX: SPK), the third-worst performer in terms of share price moves.

Shares in New Zealand's largest telecommunications and digital services company closed on 30 August trading at $3.33 apiece. On 30 September, the ASX 200 stock ended the day trading for $2.82 a share.

This saw the Spark share price down 15.3% over the month.

The last price-sensitive news from Spark came on 23 August, when the company reported its FY 2024 results.

Core metrics included revenue of $3.86 billion, down 14% from FY 2023 on a reported basis, along with a 72% year-on-year slide in reported net profit after tax (NPAT), which came in at $316 million.

Investors punished the stock on the day, and it's been in a downward trend since. With shares down 2.3% so far in October, the Spark share price is trading 38% lower in a year.

Moving on to the second-worst ASX 200 stock to hold in September, we have Light & Wonder Inc. (ASX: LNW).

Shares in the gaming company closed August at $161.00 and ended September trading for $132.63. That put the Light & Wonder share price down 17.6% over the month.

Most of that pain was delivered on and following 23 September. Heading into that date, Light & Wonder shares were up 2.4% for the month.

On 24 September, however, shares ended the day down 18.4% after the company released an update on the United States lawsuit filed by rival ASX 200 gaming stock Aristocrat Leisure Limited (ASX: ALL).

In a nutshell, Aristocrat claims that Light and Wonder's Dragon Train game infringes on the copyright of its own Dragon Link game. Investors pummelled the Light & Wonder share price after learning that the US court granted a preliminary injunction against its game.

Light & Wonder said it intended to appeal the decision.

Despite shares sliding another 5.3% so far in October, the Light & Wonder share price remains up 14% over 12 months.

Trailing the pack

Which brings us to the ASX 200 stock with the worst share price performance in September, Star Entertainment Group Ltd (ASX: SGR).

Now, this one's a tad tricky, as Star shares entered a trading halt on 29 August at 45 cents. Star stock didn't resume trading until 27 September. So there weren't a whole lot of trading days in the month.

There was plenty of action, though, and the casino operator's share price ended September at 29.5 cents, down 34.4% for the month.

The lion's share of that pain was delivered on the first day it resumed trading.

After market close on 26 September, Star announced its delayed FY 2024 results along with a separate release detailing an agreement on a new high interest debt facility for up to $200 million.

With the company reporting a statutory net loss for FY 2024 of $1.68 billion, driven by a non-cash impairment charge of $1.44 billion, investors were quick to hit the sell button.

And with Star shares falling another 6.7% so far in October, the ASX 200 stock is now down 55% over the past 12 months.