Decoding the MOS Formula in Weekly Options Trading: MOS, PG, SITE Surge

Understanding the “mos formula” for options activity reveals a consistent pattern in this week’s trading. When calculating the significance of options volume, traders compare daily contract activity against historical baselines—this formula helps determine whether unusual concentration exists. Russell 3000 components are showing exactly this kind of notable spike in options trading, particularly across three major equities.

MOS Options Trading Volume Breaks Above Average

Mosaic Co (MOS) has captured significant options attention early this week. The stock generated 30,506 options contracts, translating to approximately 3.1 million underlying shares—a figure that represents 43.2% of MOS’s typical daily options volume. The concentrated trading activity reveals a distinct preference: the $27.50 strike call option expiring February 20, 2026 attracted 3,287 contracts alone, equivalent to roughly 328,700 shares. This February 20 expiration window has become a focal point for options traders, with just two weeks remaining until these contracts expire.

PG and SITE Follow a Remarkably Similar Pattern

The mos formula pattern—where daily volume substantially exceeds monthly averages—repeats across other major holdings. Procter & Gamble (PG) recorded 44,592 options contracts this week, representing 4.5 million underlying shares or 43.1% of its average daily options volume of 10.3 million shares. The dominant position mirrors MOS activity: PG’s $145 strike call option expiring the same February 20 date saw 6,089 contracts (608,900 underlying shares). Similarly, SiteOne Landscape Supply (SITE) generated 2,449 contracts (244,900 shares), representing 42.6% of its typical daily volume—with the $140 strike call option for the same expiration capturing 1,965 contracts (196,500 underlying shares).

The Formula Behind February 20 Expiration Interest

The alignment across these three positions reveals why the mos formula matters: options expiring February 20, 2026 are approaching their critical two-week window. During this final fortnight before expiration, options activity typically concentrates around specific price strikes as traders adjust positions. All three companies showing coordinated high volume in identical expiration contracts suggests institutional rebalancing or systematic hedging strategies at work. This synchronized activity pattern—where multiple Russell 3000 components spike simultaneously at matching strike prices—underscores the importance of tracking options concentration metrics as indicators of broader market positioning.

For detailed options data across various expirations, traders can access comprehensive analytics through specialized platforms. The consistent pattern observed in MOS, PG, and SITE demonstrates how applying the mos formula—comparing current volume against historical norms—helps identify significant positioning shifts ahead of major expiration dates.