Ameren shorts near a year high, calls dominate options

Short sellers have rebuilt a meaningful position in Ameren Corporation over the past month, even as the stock climbs and options traders lean heavily toward calls.

Short interest reached 5.6% of the free float on October 20, up 21% over the past month. The build accelerated sharply in early October: shares short jumped from around 12.4 million at the start of the month to more than 15.2 million by October 20. For a regulated utility whose earnings are shaped by rate cases rather than economic cycles, that pace is unusual. The cost to borrow has risen 30% over the past week to 0.49%, reflecting higher demand from new shorts rather than any tightening in supply. Availability remains exceptionally loose at roughly 1,059%, meaning about ten shares are available to lend for every one already borrowed. The ORTEX short score has crept up alongside the position, reaching 51.2 on October 20 from 47.1 on October 8. Shorts are paying incrementally more to hold a position that faces no mechanical squeeze pressure.

Options positioning tells a sharply different story. The put/call ratio dropped to 0.27 on October 20, two full standard deviations below its 20-day average of 0.45 and the lowest reading of the past 52 weeks. That is an unusually call-heavy configuration for a utility, and it sits directly at odds with the growing short book. The divergence between a rising short position and heavy call demand is the clearest tension in AEE right now, with November 5 earnings fifteen days out.

The Street is broadly constructive but has been trimming targets. Morgan Stanley raised its target marginally to $109 on October 21 while maintaining an Equal-Weight rating. BMO Capital cut its target from $119 to $113 this week, holding Outperform. Barclays also lowered, from $117 to $109, keeping Equal-Weight. The pattern across the past month has been consistent: most firms kept positive or neutral ratings but marked down price targets, with the consensus mean now at $114.25 against a current price of $106.23. The stock trades at a P/E of 18.6x, up roughly 0.7 points over the past 30 days as the price recovered. On factor scores, the dividend rank stands at the 97th percentile, a reflection of the yield and consistency that keeps the institutional base stable. EPS momentum ranks in the 38th percentile over 30 days, suggesting estimates have not been moving in the company's favour.

The largest institutional holders added shares in the most recent quarter. T. Rowe Price lifted its position by 3.9 million shares to hold 11.8% of the company. BlackRock added 2 million shares to reach 9.3%. State Street increased by roughly 396,000 shares. Those flows run in the opposite direction to the short build and help explain why the borrow pool remains so ample: large passive holders tend to lend their stock, keeping availability high even as short interest rises. Insider activity over the past 90 days produced a net sale of around 8,000 shares worth roughly $877,000, a modest figure dominated by planned disposals rather than discretionary selling, one sale by the Group President of Utilities was conducted under a 10b5-1 plan.

The stock gained 1.8% over the past week to close at $106.23, slightly behind the median of its closest regulated utility peers. WEC rose 2.7% over the same period, CMS gained 3.2%, and Consolidated Edison added 3.9%. Ameren's one-month gain of 3.9% is more in line with the group. The previous two earnings prints produced muted one-day moves of less than 1% in each direction, which gives options traders a relatively low bar for the November 5 release.

The EPA's Clean Air Markets data flags a record-low gross capacity factor for Ameren's power units in June 2026, the smallest June reading since 2024. That is a factual data point from Ameren's own operating profile, though none of the alternative datasets covering the company has been measured to lead its reported revenue figures.

What matters most between now and November 5 is whether the short book continues to grow or begins to unwind, and whether the call-heavy options positioning reflects genuine conviction or simply low-cost speculation ahead of what have historically been small earnings moves.