SLS Stock Logs Best Day In Over 2 Weeks: Citigroup Builds Nearly $5M Stake Ahead Of Key AML Trial Trigger

• Citigroup disclosed 326,591 shares worth $4.82 million, boosting its stake by 1,173%.
• Sellas’ Phase 3 Regal AML trial is two events away from triggering final analysis.
• A recent legal loss against 3D Medicines tempered optimism, though their GPS partnership remains intact.

Shares of Sellas Life Sciences (SLS) logged their best session in more than two weeks on Monday after Citigroup disclosed a nearly $5 million stake, adding to investor interest as the biotech firm approaches a key Phase 3 acute myeloid leukemia (AML) trial catalyst.

SLS stock jumped 12% on Monday to $11.22, marking its highest levels in over a week. 

Citigroup Builds Nearly $5M SLS Stake

Citigroup reported owning 326,591 SLS shares worth $4.82 million as of June 30, according to Fiscal AI data disclosed Monday. The bank added 300,945 shares from its previously reported position, expanding its stake by 1,173%. Citigroup was the largest investor among the five Sellas positions disclosed on Monday and tracked by Fiscal AI. Together, these holdings comprised 554,334 shares valued at $8.19 million as of June 30. 

Vontobel Holding held 146,762 shares worth about $2.17 million, or 0.08% of Sellas. The firm reduced its stake by 27,391 shares, representing a 16% decline in its shareholding. Despite the reduction, the market value of Vontobel’s remaining position increased by $1.43 million during the quarter, reflecting the appreciation in SLS shares.

Monday’s disclosures also included three smaller positions. Walleye Capital reported 30,116 shares valued at $444,512, while Walleye Trading held 28,965 shares worth about $427,523. Ridgewood Investments disclosed 22,500 shares valued at $332,100.

Sellas AML Trial Nears Final Analysis

Sellas’ main catalyst remains its Phase 3 Regal trial of galinpepimut-S (GPS) in acute myeloid leukemia. The study has recorded 78 of the 80 events needed to trigger final analysis. With overall survival as the primary endpoint, CEO Angelos Stergiou has said slower event accumulation could be encouraging. Regal would meet its target if GPS extends median survival to 12.6 months from eight months under standard treatment.

Sellas had an estimated $138.3 million in cash and equivalents as of June 30, including $28.7 million raised through warrant exercises. Meanwhile, updated executive change-of-control provisions have fueled retail takeover speculation.

Legal Setback Tempers SLS Bullish Setup

Meanwhile, an arbitrator recently dismissed Sellas’ claims against Chinese partner 3D Medicines and ordered it to pay about $1 million toward the partner’s legal costs. The dispute involved $13 million in GPS milestone payments. However, the partnership remains intact, with 3D Medicines continuing to develop GPS in Greater China. Sellas says $191.5 million in potential future milestones remains under the agreement, including the disputed amount.

How Do Retail Traders Feel About SLS?

On Stocktwits, retail sentiment for SLS flipped to ‘bullish’ from ‘bearish’ levels a day ago amid nearly a 400% surge in 24-hour message volumes.

One user said, “$SLS To everyone wondering what’s going on, I’d say... nothing more than what was announced. The second half of 2026 is poised to be one of the most catalyst-rich periods in SELLAS history. We are strategically transitioning from a clinical-stage biotech company into a late-stage organization on the cusp of commercialization”

Another user said, “$SLS we need to practice some patience. Did we have a strong day as bulls? Yes. Did the majority of the market push upwards today? Yes. Are we still down from our 15+ high a month ago? Yes.”

SLS stock has rocketed 576% over the past year. 

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