Why Is SELLAS LIFE SCIENCES (SLS) Stock Up Today?

SLS stock surged 15.37% to $15.46 on Thursday, driven by a strong intraday rally and renewed investor interest in its cancer vaccine pipeline. The stock opened with a modest 1.0% gap up and climbed steadily throughout the session, fueled by anticipation around the REGAL trial data and a broader positive sentiment in the biotech sector. The move came as the stock has gained over 20% in the past five days, marking its best weekly performance since early July.

What Happened

SLS opened at $13.54, up from the prior close of $13.40, and traded as high as $15.67 before settling at $15.45. The stock’s sharp rise was supported by a significant increase in trading volume, with 13.7 million shares exchanged, 1.7 times its 3-month daily average. The rally followed a recent 28.1% price increase over the last eight sessions, lifting the stock from $11.62 to $14.89. A single large options print of $4.1 million in call premiums also signaled strong bullish positioning. Meanwhile, retail traders on platforms like r/wallstreetbets have expressed heightened interest in the stock, with some describing their positions as “all in.”

What The Data Shows

The stock has printed 56 fresh 52-week highs and 20 fresh 52-week lows on August 21, 2026, reflecting a volatile but upward trend. Over the past 30 days, sentiment has improved from an average of 56 to 63 out of 100. SLS remains unprofitable with a trailing twelve-month EPS of -0.21 and a high beta of 2.49, indicating strong sensitivity to market swings. Despite a recent earnings miss and a legal setback involving a $1 million arbitration loss, the stock has continued to attract speculative attention.

What To Watch

Investors should monitor the upcoming REGAL trial data, which could provide a key catalyst for further price movement. Coverage breadth is limited, with only one story published in the last 36 hours, but increased options activity and retail chatter suggest growing interest in the stock.