5 Mid-Cap Stocks With the Highest Gains in April

In this article, we will list the 5 Mid-Cap Stocks With the Highest Gains in April. Please visit 7 Mid-Cap Stocks With the Highest Gains in April if you’d like to see an extended list and how we compiled it.

5. Sigma Lithium Corporation (NASDAQ:SGML)

With a 67.83% gain in April, Sigma Lithium Corporation (NASDAQ:SGML) has secured a spot on our list of the mid-cap stocks with the highest gains in April.

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On April 2, 2026, BofA upgraded Sigma Lithium’s stock to “Buy,” raising its price target from $14 to $17. This carries significant weight for a stock facing one of the harshest commodities cycles in recent memory. A $50 million prepayment agreement was signed in conjunction with Q4 earnings, which BofA noted as the pivotal moment. This agreement would give Sigma Lithium Corporation (NASDAQ:SGML) confidence to overcome its short-term liquidity crisis, resume regular operations, and accelerate Phase 2 capital spending alongside the ongoing Phase 1 ramp.

Due to a purposeful mining restructure, full-year 2025 production of high-grade premium lithium oxide was 183,000 tons, a 24% decrease from 2024. By turning dry stack tailings into high-purity lithium fines, Sigma Lithium Corporation (NASDAQ:SGML) was able to overcome the drop in volume and generate an extra 70,000 tons in revenue value. Operating cash flow increased 35% sequentially to $31 million in Q4 as a result of annual and quarterly cost reductions of 21% and 77%, respectively. Additionally, the company significantly strengthened its balance sheet by repaying 35% of its overall debt and 60% of its short-term debt during the year.

A $96 million working capital offtake for 2026 deliveries further supports near-term operations, while the $50 million prepayment, which covers 40,000 tons annually over three years, directly reduces the financial overhang that had caused investors to be cautious.

Sigma Lithium Corporation (NASDAQ:SGML) projects $218 to $260 million in free cash flow at current lithium pricing from Phase 1 alone, with Phase 2 capacity potentially doubling output. BofA’s increased conviction shows a company that has quietly strengthened its financial foundation while the market was focused elsewhere.

Sigma Lithium Corporation (NASDAQ:SGML) engages in the exploration and development of lithium deposits in Brazil, through which it serves the lithium-ion battery supply chain for the EV industry.