Event Gaps: Gemini 2.5 Pro's picks for 2026-09-08
Gemini 2.5 Pro picked BE, TTD, BLDR, TAP, ILMN for a 1-day horizon. Intraday alpha vs SPY: -1.62%. Picks with positive alpha: 20%.
| Experiment | Event Gaps |
|---|---|
| Model | Gemini 2.5 Pro |
| Prompt version | event-gap-v1 |
| Asked | |
| Horizon | 1-day |
| Measured from | 2026-09-04 |
| Measured to | 2026-09-08 |
| Benchmark | SPY |
| Status | Settled |
| Intraday alpha vs SPY | -1.62% |
| Picks with positive alpha | 20% |
| Benchmark return | -0.40% |
The picks
| Rank | Symbol | Gap direction | Price change | Return in the called direction | Confidence | vs benchmark | Called right |
|---|---|---|---|---|---|---|---|
| 1 | BE | up | +3.53% | +3.53% | 95% | +3.94% | Yes |
| 2 | TTD | down | -2.09% | -2.09% | 90% | -1.69% | No |
| 3 | BLDR | down | -4.60% | -4.60% | 85% | -4.20% | No |
| 4 | TAP | down | -3.50% | -3.50% | 85% | -3.10% | No |
| 5 | ILMN | up | -3.47% | -3.47% | 80% | -3.07% | No |
The model's market view
The long Labor Day weekend provides ample time for the market to absorb Friday's post-market S&P 500 rebalancing announcements. This quarterly event forces index-tracking funds to adjust holdings, leading to substantial opening gaps for added and deleted constituents on Tuesday morning. Inclusions like Bloom Energy and Illumina will gap up due to guaranteed passive inflows, while deletions like Molson Coors and The Trade Desk face intense selling pressure at the open.
Why each pick
BE
Bloom Energy was added to the S&P 500 in the quarterly rebalance announced Friday evening. As a major addition with a large market cap, it will attract billions in forced buying from passive index funds, setting up a massive gap up at Tuesday's open.
TTD
The Trade Desk was surprisingly removed from the S&P 500 during Friday's rebalance announcement. Being demoted from the benchmark index forces widespread liquidation from large-cap tracking funds, which almost certainly guarantees a sharp gap down at the next open.
BLDR
Builders FirstSource was removed from the S&P 500 index and transitioned out on Friday evening. Deletions face severe liquidity drains as indexers dump the stock. This removal was a surprise to many, guaranteeing a strong gap down due to mechanical selling.
TAP
Molson Coors Beverage is being demoted from the S&P 500 in favor of larger growth names. The loss of S&P 500 constituent status triggers forced selling that will heavily gap the stock down at the Tuesday open as market makers front-run the institutional outflows.
ILMN
Illumina was selected for inclusion in the S&P 500 index. This transition forces passive index funds to acquire shares ahead of the September 21 effective date. Shares immediately ticked up 2% in after-hours trading and will gap up on Tuesday.
Other models on the same run
| Model | Picks | Intraday alpha vs SPY | Picks with positive alpha |
|---|---|---|---|
| GPT-5.6 Sol | BE, HUBS, P, ILMN, BLDR | -0.77% | 40% |
| Muse Spark 1.1 | LULU, AVGO, PATH, GWRE, ZS | -2.12% | 40% |
| Grok 4.5 | UNFI, ABM, CAN, DLNG, CASY | +1.70% | 40% |
| DeepSeek R1 | UNFI, CASY, GME, ABM, BRZE | +0.53% | 20% |
Written up on ForecastNest Insights: Event Gaps: Gemini 2.5 Pro's picks for 2026-09-08.
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