Reddit Inc. (RDDT) is having a good Friday. The social media platform's stock is climbing after S&P Dow Jones Indices announced late Thursday that Reddit will be added to the S&P 500 index. The move is set to take effect before the opening bell on Tuesday, August 18.

The broader market is also feeling optimistic, with Nasdaq futures up 0.20% and S&P 500 futures gaining 0.09%.

Reddit's Ticket to the Big Leagues

So, why the index change? It's all about a merger. AvalonBay Communities Inc. (AVB) is merging with fellow S&P 500 member Equity Residential (EQR) in a merger of equals. Shareholders from both companies gave the deal a thumbs up this week, with more than 99% of votes cast at each company's special meeting in favor.

The transaction could close as soon as Monday. Under the deal terms, each AvalonBay share will convert into 2.793 units of Equity Residential stock.

Once the merger is complete, the combined company will drop both existing names and take on a new one: Vivmark Residential. It will trade on the NYSE under the ticker VMRK starting August 18, and it will keep its spot in the S&P 500 rather than exit the index.

That's where Reddit comes in. With AvalonBay leaving the index, there's an open seat, and Reddit is sliding right into it. It's a big deal for the company, which has been public for just a couple of years and is now joining the ranks of the most widely tracked stocks in the world.

What the Charts Say About Reddit (RDDT)

For traders, the question now is whether this rally has legs. Let's look at the technical picture.

Reddit is trading 5.2% above its 20-day simple moving average (SMA) of $166.00 and 6.8% above its 100-day SMA of $163.45. But it's still 2% below its 200-day SMA of $178.07, which means the longer-term trend line is the next big hurdle. The stock is also essentially flat versus the 50-day SMA of $174.85, sitting just 0.2% below it. So this rally is happening right at a "decision zone" where breakouts can either stick or fade.

The bigger-picture moving-average structure is still a headwind. The 20-day SMA remains below the 50-day SMA, which is bearish, and the death cross that occurred in March (when the 50-day fell below the 200-day) signals the longer-term trend has been under pressure. That said, a strong push through the 200-day area would be a meaningful character change because it would put price back above the most-watched long-term average.

Here are the key levels to watch:

• Key Resistance: $186 — a nearby round-number zone where rebounds can stall, especially with the 200-day SMA ($178.07) still overhead.
• Key Support: $152.50 — a prior buyer-defense area that sits well below current price, making it a key "line in the sand" if the gap starts to unwind.

RDDT Price Action: Reddit shares were up 10.99% at $175.49 during premarket trading on Friday, according to market data.

So, is this the start of a new chapter for Reddit? The index inclusion is certainly a milestone, and the market is reacting positively. But as the technicals suggest, there's still work to do. The 200-day SMA is looming, and how the stock handles that level could determine whether this is a breakout or just a brief pop.