Fabrinet builds high-speed optical transceivers under contract, mostly in Thailand, for the networking vendors that sell them to hyperscale data centers. On 17 August it reported record quarterly revenue of $1.32bn, up 45% year on year, with data-center work now more than half the total — and then guided the December quarter to about 6% sequential growth. Its shares fell more than 20% the next session, and the semiconductor companies whose silicon goes inside those modules fell with it.

What did not move is the more useful fact. Over the five sessions to 21 August, Nvidia lost 3.6%, Broadcom 7.4% and Qualcomm 1.7%. Over the same stretch Fabrinet fell 26.3%, Coherent 17.4%, Credo 18.2% and Applied Optoelectronics 19.2%. The drawdown stopped at the interconnect layer. It coincided with the 30-year Treasury yield topping 5.31%, a 19-year high, a duration shock that lands hardest on the longest-dated growth stories — which is exactly what these are.

Three businesses, all accelerating

SiTime replaces quartz crystals with silicon oscillators and clock chips built on micro-electromechanical systems, and its content per AI server dwarfs its content per phone. Revenue grew 126.5% in the June quarter to $157.4m, the fourth consecutive quarter of acceleration from 44.8% a year earlier. Gross margin reached 63.0%, up roughly 950 basis points over that span. Its communications, enterprise and data-center line hit $101.2m, or 64% of revenue, up 181%. On 1 July it closed the $1.5bn purchase of Renesas's Timing Product Division, removing its most direct clock-chip rival and adding a business it says runs at 70% gross margin. The risks are its own: one consumer customer supplied $22.8m of revenue last quarter, and the carve-out still depends on Renesas for manufacturing and test.

MACOM sells analog chips across radio frequency, microwave and lightwave into three end markets, and that mix is the point. Data center reached $137.6m in the July quarter — about 40% of revenue — alongside a record $133.4m of industrial and defense and $71.3m of telecom. Total revenue grew 35.8% to $342.2m, gross margin expanded for a fourth straight quarter to 58.3%, and operating income more than doubled on that 36% revenue growth. Book-to-bill printed a record 1.6-to-1, with 800-gigabit and 1.6-terabit platforms dominating orders. Top-ten customers are now under 40% of revenue.

MaxLinear sells communications chips for broadband modems, Wi-Fi and optical transceivers. Its infrastructure line grew about 145% to roughly $85m on Keystone, a digital signal processor for 100-gigabit-per-lane optical links now in volume production at US and Asian hyperscalers; only three vendors ship such parts at volume. Guidance for the September quarter of $210-220m compared with roughly $174m of consensus.

What the price now pays for

Earnings multiples are useless here — SiTime's trailing price/earnings ratio is above 1,000x on near-zero GAAP profit and MaxLinear's is negative — so the honest comparison is price per dollar of trailing gross profit, and all three earn between 58% and 63%.

MACOM trades at 30.8x, against roughly 49x three months ago and 34x six months ago, while its trailing gross profit has grown 18% since February. That is the one place where price has moved decisively against the business. SiTime, at 58.6x trailing and 31.3x forward, is a third cheaper than in May but back to where it stood in February, and remains the most expensive name in the group; its forward figure also embeds acquired revenue. MaxLinear is the cheapest at 18.0x trailing and 13.8x forward, but it stood near 6x in February before a 324% twelve-month run — against that anchor, August unwinds a re-rating rather than creating a gap.

The path matters too. Of MaxLinear's 26% fall over the past month, 24 points came on 18 and 19 August, and the shares had risen 25% in the week before, from $69.16 on 11 August to $86.46 on 17 August, with no news of their own; the quarter was reported on 23 July. SiTime is still up 3.1% over thirty days despite surrendering its entire post-earnings gain. This was two sessions, not a grind.

The setup

Where it stands — Three accelerating businesses were repriced together on a contract manufacturer's guidance and a bond-yield shock, not on their own results. Would confirm — MACOM's October quarter landing inside its $415-425m guide with data-center revenue up another 35% sequentially. Would invalidate — Book-to-bill falling below 1.0 at MACOM, or SiTime's data-center line failing to grow sequentially in Q3. Watch next — MACOM's fiscal fourth-quarter report in early November; SiTime guided Q3 to $285-295m at about 68% gross margin. Valuation — MACOM 30.8x trailing gross profit and 27.0x forward, against about 49x in May; SiTime 58.6x; MaxLinear 18.0x.