SLS Stock Jumps Overnight After New Investor Disclosure – Retail Flags ‘Massive’ Options Bet Ahead Of AML Data

• Armstrong Advisory Group disclosed a new SLS position of 380 shares, worth about $5,610.
• Sellas’ Phase 3 REGAL trial has reached 78 of the 80 deaths needed for final analysis.
• Retail traders flagged heavy September $30 call activity, including a reported $5.8 million bet.

Shares of Sellas Life Sciences (SLS) rose 1% overnight heading into Tuesday, driven by a newly disclosed institutional position, while retail traders pointed to a “massive” call options wager ahead of the drugmaker’s acute myeloid leukemia (AML) readout.

SLS stock slipped 1% on Monday, marking its third straight session of losses. 

Armstrong Adds New SLS Stake

Quiver Quantitative data shows that Armstrong Advisory Group held 380 SLS shares worth about $5,610 as of June 30, marking a newly reported position in the biotech firm.

The main catalyst for SLS is its Phase 3 Regal trial of galinpepimut-S (GPS) in AML. The event-driven study has reached 78 of the 80 deaths required to trigger its final analysis, placing the company close to one of the most consequential clinical readouts in its history. Sellas has previously said that the trial would be considered successful if GPS extends median overall survival to 12.6 months, compared with eight months under best available therapy.

CEO Angelos Stergiou has pushed back recently against claims that slower event accumulation reflects stronger-than-expected survival in the control arm. “Statistically, it is likely plausible that slower accumulation may be a signature of a highly effective active arm,” Stergiou said on LinkedIn.

He said that GPS could produce a durable “long tail” in survival, similar to the company’s Phase 2 data, in which patients in second complete remission achieved a median overall survival of 21 months. Stergiou also rejected the idea of stopping the study at 78 events. “Events are our statistical currency,” he said, arguing that the final events are needed to preserve the study’s statistical power and avoid questions over timing bias.

SLS Call Volume Sparks Squeeze Talk

Meanwhile, retail attention has focused on activity in September $30 calls. One Stocktwits user called 25,000 contracts priced at $2.32 a “massive $5.8M bet,” pointing to an estimated break-even level of about $32.32 by the Sept.18 expiration.

On Stocktwits, retail sentiment for SLS has been ‘bullish’ over the past week amid over a 600% surge in monthly message volumes, while watchers have also risen 5% over the same period.

Another trader called the options volume “astonishing” and said that a positive top-line release could set up a sharp squeeze. A separate user said, “Someone knows something good is on the horizon,” while flagging a $40 million options move.

SLS Deal Speculation Grows 

The approaching readout has also kept partnership and acquisition speculation active among retail investors. Traders have been parsing Sellas’ updated executive severance and change-of-control arrangements, including lump-sum treatment for certain CEO payments and compensation protections for other senior executives.

Stergiou’s Fourth of July LinkedIn post added to that chatter after he thanked Sellas’ “strategic partners” and said he was “incredibly optimistic about the future.”  Sellas enters the catalyst with a stronger balance sheet than in prior years. The company ended the first quarter with $107.1 million in cash and raised another $28.7 million through warrant exercises in April and May.

SLS stock has surged 586% over the past year. 

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