Monolithic Power Systems, Inc. (NASDAQ: MPWR) ended Friday’s session higher and then held essentially flat in after-hours trading, closing the week on a day when market mechanics—notably the year’s big options expiration—can distort volume and late-day price action. MPWR closed at $937.11, up 0.82% on the day, and was unchanged at $937.11 in after-hours trading as of 6:07 p.m. ET. 1
Because Dec. 19, 2025 is a Friday, U.S. markets will be closed over the weekend. The next regular session is Monday, Dec. 22, 2025—and that matters for MPWR, because the stock is set to join the Nasdaq-100 at the open as part of the index’s annual reconstitution. 2
Below is what investors should know heading into the next market open, including today’s most relevant analyst call and the key catalysts likely to shape Monday’s trading.
MPWR after-hours check: where the stock finished and how it traded into the close
MPWR’s Friday tape showed two notable features: a strong intraday rally that faded into the close and an unusually large spike in volume.
- Close: $937.11 (+0.82%) 1
- After-hours: $937.11 (flat) 1
- Day’s range: $937.11 low to $966.33 high (about a 3.1% intraday spread) 1
- Volume:5.53 million shares, versus 731k the prior day 1
One detail traders often watch: MPWR closed at the day’s low ($937.11). That doesn’t automatically signal weakness, but it can hint at late-session repositioning—something that can be amplified on major derivatives-expiration days. 1
The biggest “today” forecast: Truist raises MPWR price target to $1,375
The most market-relevant, stock-specific research item dated today was a Truist Securities call raising its price target on Monolithic Power Systems to $1,375 from $1,163, while keeping a Buy rating. 3
Truist framed MPWR as an AI infrastructure “derivative” play, arguing that next-generation GPU/XPU platforms require higher-density power delivery and that MPWR’s power solutions position it to benefit from ongoing buildouts in AI data centers. 3
Two additional points from Truist’s note are worth highlighting ahead of Monday:
- The bull case is not “frictionless.” Truist explicitly flagged the practical constraints around “finding the power” to run AI infrastructure and the funding required to build it—yet still argued AI infrastructure semiconductor names remain attractive relative to growth. 4
- The note said Truist adjusted targets across the semiconductor/AI group after establishing 2027 estimates, implying a longer-run lens rather than a one-quarter trade. 4
For context, MarketWatch-listed analyst data showed an average price target around $1,201 with an “overweight” consensus recommendation (per FactSet data presented there). Truist’s $1,375 target sits above that aggregate midpoint. 5
Why did volume explode today? Triple/quadruple witching is a big part of the answer
Friday, Dec. 19, 2025 was the quarter’s major derivatives expiration day—commonly referred to as triple witching (and often still called quadruple witching historically). This event is known for very high trading volume, particularly into the close, as investors roll hedges, rebalance, and close positions. 6
Axios reported that more than $7 trillion in derivatives exposure was expiring, noting that these days tend to be high-volume and not necessarily high-volatility in a historical sense. 6
That matters for MPWR because Friday’s 5.53 million shares traded can reflect index and options-related flows as much as pure fundamental conviction. 1
Sector backdrop: tech and semiconductors rebounded, helping AI-linked names
MPWR didn’t trade in isolation. Reuters described a session where technology shares rebounded, helped by strength tied to AI-related sectors and a strong forecast-driven move in Micron, lifting broader chip sentiment. Reuters also noted that stocks saw added volatility due to triple witching. 7
Given MPWR’s exposure to power solutions used in cloud and server AI applications, a risk-on tone in semiconductors can spill over into the stock—even on days without company-specific headlines. 8
The key Monday catalyst: MPWR is set to join the Nasdaq-100 on Dec. 22
This is the “mechanical” catalyst most likely to matter before the next open.
Multiple reputable outlets reported that Monolithic Power Systems will be added to the Nasdaq-100, effective prior to market open on Monday, Dec. 22, 2025, as part of the index’s annual reconstitution. 2
Why investors care:
- Funds that track the Nasdaq-100 (and products benchmarked to it) typically need to buy new constituents around the effective date.
- That can create temporary demand and abnormal volume, sometimes spilling into the close before inclusion and into the first sessions after inclusion.
Important nuance: index inclusion can be a real flow driver, but it does not change MPWR’s fundamentals by itself. The market often prices in some of the effect early, and the actual trading impact can vary widely by stock and by how crowded the trade already is.
Fundamentals refresher: what MPWR does and the last major company guidance
Monolithic Power Systems is a fabless semiconductor company focused on power electronic solutions—DC/DC, AC/DC, power management ICs, and related products used across enterprise data, storage and computing, automotive, communications, consumer, and industrial markets. 8
The last major fundamentals update (ahead of today) came with the company’s most recent outlook. Reuters reported that on Oct. 30, MPWR forecast Q4 sales of $730 million to $750 million, above analysts’ average estimate cited by LSEG, with strength linked to AI-driven data center expansion and power management demand. 9
That older guidance is still relevant because, absent fresh earnings, it remains the clearest official directional signal investors have for near-term operating momentum.
Dividend and calendar items that can matter before year-end
While not an “after-hours mover” today, MPWR’s dividend timeline is approaching a key date.
In its Dec. 12 dividend announcement, MPWR declared a $1.56 per share quarterly dividend, payable Jan. 15, 2026, to stockholders of record as of Dec. 31, 2025. 10
Also, several market calendars list MPWR’s next earnings report in early February. Nasdaq’s earnings page shows an estimated earnings date of Feb. 5, 2026 (noting it’s algorithm-derived and subject to change). 11
What to watch before the next market open
Here’s a practical checklist for Monday, Dec. 22 (the next U.S. session):
1) Nasdaq-100 inclusion flows and early-session volatility
With MPWR joining the Nasdaq-100 at the open, watch for:
- Heavy opening prints
- Fast reversals after an initial spike
- Higher-than-normal volume continuing from Friday’s expiration dynamics 2
2) Follow-through (or fade) from Truist’s bullish target reset
Truist’s $1,375 target is a clear “headline number” that can travel through trading desks and social feeds over the weekend. Whether the stock holds gains often depends on whether Monday brings:
- broader chip strength, or
- a rotation away from high-multiple AI-linked names. 3
3) Key technical levels from Friday’s range
Even fundamental investors often track these levels as “decision points”:
- ~$937 (Friday’s low/close) as near-term support
- ~$966 (Friday’s high) as near-term resistance 1
4) The broader AI/semiconductor tone
Reuters emphasized the role of AI-linked momentum in Friday’s market rebound. If semiconductor sentiment remains constructive into Monday, MPWR can benefit by association—especially given its positioning in power solutions used in server AI applications. 7
Bottom line for Monday: MPWR has catalysts, but expect “noisy” price action
MPWR ended Dec. 19 with a modest gain and flat after-hours trading, but the setup into Monday is unusual: post-expiration positioning plus Nasdaq-100 inclusion can create price action that looks “fundamental” even when it’s largely mechanical.
If you’re watching MPWR into the next open, the most important near-term drivers are:
- index inclusion flows,
- the market’s appetite for AI infrastructure beneficiaries, and
- whether Friday’s heavy volume was a one-day expiration effect—or the start of a more sustained repricing sparked by the new Truist target. 2
