If you spent any time watching the S&P 500 tickers this past October, you probably noticed the "afternoon shiver." It’s that weird, jittery price action that hits right around 3:00 PM ET. Honestly, it's not ghosts in the machine. It’s the massive surge of zero-days-to-expiration (0DTE) options hitting the tape.
By October 2025, the 0DTE landscape didn't just grow; it basically became the market. According to Cboe Global Markets data from late 2025, these same-day contracts now represent a staggering 59% of total SPX volume. That is a wild jump from just a few years ago. We’re talking about an average of 2.6 million SPX 0DTE contracts trading every single day.
The Big Regulatory Shift: Goodbye $25k PDT Rule?
The most massive piece of 0DTE options news October 2025 brought wasn't actually a price move. It was a piece of paper from FINRA. For decades, retail traders have been haunted by the "Pattern Day Trader" (PDT) rule. You know the one: keep $25,000 in your account or you're limited to three day trades a week.
Well, in late 2025, FINRA finally moved to replace the old PDT framework with something called the Intraday Margin Rule. Basically, they realized that the $25k floor was a relic of the dot-com era that didn't make sense in a world of high-speed 0DTE trading.
Instead of a hard dollar cap, the new proposal—filed with the SEC in late 2025—shifts toward real-time risk monitoring. They’re moving to apply maintenance margin rules to positions while they are open during the day, rather than just looking at your closing balance. For the average person trading 0DTEs in their pajamas, this is huge. It levels the playing field, but it also means your broker might be way faster to liquidate you if a trade goes south at 2:00 PM.
Why October Felt So Different for Traders
If you were trading in October, you might have felt like the "Gamma Squeeze" was happening every other Tuesday. You weren't imagining things.
A specific phenomenon peaked this month: the Short Iron Condor surge.
Retail traders have been flocking to this strategy—selling a call spread above the market and a put spread below—to collect premium. It’s "free money" until it isn't. On October 10, when tariff news sparked a massive volatility spike, the total US options volume hit a record 110 million contracts.
When the market starts moving fast, the market makers who sold those 0DTEs have to hedge. Fast.
UBS strategists noted that in October, dealer gamma often surged to nearly $90 billion in the final ten minutes of trading. To stay neutral, these big banks have to buy or sell billions of dollars worth of S&P 500 futures in seconds.
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"There were several sessions in October where the market struggled to break above levels where long gamma was concentrated. But once the options expired after the close, the index often rallied more freely." — Kieran Diamond, UBS Derivatives Strategist.
The "Speed Bump" Effect
One of the weirdest bits of 0DTE options news October 2025 is how these trades are actually suppressing big rallies.
Think of it like a speed bump. Because so many people are selling calls to earn "rent" on their stocks, market makers end up "long gamma" at certain price levels. This forces them to sell into strength, effectively capping how high the S&P 500 can go during the day.
It’s a mechanical drag.
If the index tries to moon, the dealers have to sell to stay hedged.
If the index dips, they have to buy.
This actually made October 2025 surprisingly stable on an intraday basis, right up until the final "Power Hour" when everyone tries to exit at once.
What Actually Matters for Your Account
Look, the 0DTE craze isn't slowing down. It's actually expanding.
Nasdaq recently pushed more 0DTE products into commodities like gold, silver, and even oil.
But the October data shows a clear warning: Theta (time decay) is getting more aggressive. In the final two hours of the day, a 0DTE option can lose 50% of its value even if the stock doesn't move. That’s the "mayfly" life cycle Schwab talks about. If you’re not out by 3:30 PM, you’re basically gambling on a coin flip.
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Moving Forward: Your 0DTE Game Plan
So, what do you do with all this? The "Golden Age" of easy 0DTE premiums is shifting into a more professional, high-speed environment. Here is how to handle the "New Normal" we saw in October:
- Watch the 3:50 PM MOC Imbalance: The "Market on Close" orders now collide with massive 0DTE gamma unwinding. If you are still in a position at 3:50 PM, expect slippage.
- Check the New Margin Rules: Keep an eye on your inbox. Your broker (Robinhood, Schwab, Fidelity) will be updating their terms soon to reflect FINRA’s new intraday margin standards. You might find you have more flexibility, but less "room to breathe" on losing trades.
- Focus on Index Options (SPX/XSP) over ETFs (SPY): October's liquidity was significantly better in the cash-settled SPX. Why? No assignment risk. You don't want to wake up Saturday morning owning 1,000 shares of SPY because your 0DTE call finished $0.01 in the money.
- Use Limit Orders Exclusively: October saw several "flash" slippage events where market orders for 0DTEs were filled 10-20x away from the last price. Never, ever use a market order in the final hour of trading.
The 0DTE world in October 2025 proved one thing: the tail is now wagging the dog. The options market isn't just a side bet anymore; it’s the engine driving the daily price of the entire US stock market.