Gerresheimer's Insider Rally: Active Ownership Deepens Stake as Auditors, Regulators, and Short Sellers Close In

Gerresheimer stock surges 42.7% after €10M insider buying, but short interest stays high and BaFin probes accounting errors. Shares still down 59.5% YoY.

Gerresheimer has become a stock divided against itself. On one side, the company’s biggest shareholder is shovelling nearly €10 million into the equity. On the other, short sellers are betting on a deeper slide, and a regulatory probe into past accounting errors has yet to be resolved. The result is a 42.7% monthly surge that feels as fragile as the balance sheet that fuelled it.

Active Ownership, the group that controls Gerresheimer through its AOC Gecko vehicle, snapped up roughly 287,000 shares in three tranches during the first week of May. The average price hovered around €25 a share. The buying spree, which tops Germany’s list of mandatory insider filings, pushed Active Ownership’s holding well above the 15% threshold and sent a clear signal that the controlling shareholder sees value where the market sees risk.

The market has taken notice — at least temporarily. After the purchases became public, the stock jumped roughly 44% over the month. But the euphoria has already started to fade. On Thursday, shares slid 4.5%, touching €25.30 before settling at €25.20. That leaves the stock still 59.5% lower than it was twelve months ago and miles below its 52-week high north of €64.

Short sellers refuse to surrender

Despite the insider buying, bearish bets remain elevated. The short interest ratio sits at about 11.4%, well above the average of recent months. While Arrowstreet Capital has trimmed its position, Millennium International Management has increased it. That dynamic makes every rally vulnerable to a sudden reversal if follow?through buying dries up.

Technically, the picture is mixed. The relative strength index has cooled to 28.1, no longer signalling an overbought condition, but the share price still languishes below its 200-day moving average of €27.47.

Restructuring steam ahead

Operationally, Gerresheimer is pushing through a significant overhaul. Its glass plant in Chicago Heights is scheduled to close by the end of 2026, eliminating 172 jobs. Capacity is being shifted to Italy and India as part of a wider plan to reorganise the US footprint and free up capital.

The centrepiece of that plan is the planned sale of Centor Inc., the US subsidiary that makes plastic packaging for prescription drugs. Morgan Stanley is running the process, and the company aims to close a deal before the end of 2026. Several potential buyers have already expressed interest. A successful divestment would lighten the balance sheet and sharpen the group’s strategic focus.

The accounting cloud still looms

The real test of credibility, however, will come in June 2026, when Gerresheimer is due to present its audited annual report for 2025. The company has already warned of non?cash impairments of €220 million to €240 million, linked to revenue recognition errors in so?called bill?and?hold contracts that caused revenues to be booked too early for years.

Germany’s financial regulator BaFin is investigating those misstatements for the 2024 and 2025 fiscal years, with a focus on revenue recognition and potentially misstated leasing liabilities. Until the audit is delivered, the risk of fresh negative surprises remains.

Lenders have bought time by extending the deadline for Schuldschein loans totalling about €870 million until 30 September 2026. They have also waived certain covenant tests related to the debt ratio in the meantime. That breathing space is crucial, but it does not substitute for a clean audit opinion.

Management is sticking to its operational guidance. Revenue, adjusted for acquisitions and disposals, is forecast at €2.3 billion to €2.4 billion, with an adjusted operating margin of 18% to 19%.

What happens next

The immediate inflection point is the audited annual report due in June. If no additional accounting issues emerge, the market may begin to price in the restructuring progress and the potential Centor sale. A clean result would also undercut the thesis that short sellers have been betting on.

If errors are uncovered, however, those same short sellers will be vindicated. The next scheduled check?in after the audit is the half?year financial report on 14 July 2026, when the company must deliver hard numbers on its operational performance.

For now, Gerresheimer is a bet on timing: whether Active Ownership’s conviction can outlast the regulatory, auditing and market pressures converging on the stock.