A price floor under polysilicon, a bid under solar...
On Thursday evening, August 6, 2026, President Trump signed a Section 232 proclamation that puts a hard price floor under polysilicon, the refined silicon that becomes solar cells and semiconductor wafers. The next session Sunrun rose 8.7%, Enphase 5.5%, and First Solar 2.4%. What's interesting about this? Nothing in that document changes a single cash flow until December 4. The market repriced a whole sector on the words of a public filing, and it did it twice in one week.
Policy documents move stocks the moment they can be read, months before they bite, and this week you could watch it happen in real time.
The receipt
At 21:06 UTC on August 6, about an hour after the US close, knowfir.st sent subscribers an alert on the proclamation. It read, in part: "minimum import price (MIP) program — $21/kg for polysilicon, $100/kg for ingots/wafers, $0.22/watt for solar cells, $0.38/watt for solar modules" plus "a 15% ad valorem tariff on polysilicon derivatives, effective December 4, 2026". Those are the terms of the document, quoted to subscribers the evening it was signed. Friday morning the sector gapped up, and Sunrun finished the session up 8.7%.
The alert preceded Friday's move. Everyone on Wall Street can read a proclamation. The point of the receipt is narrower: the document was public Thursday evening, the terms were quotable Thursday evening, and the repricing happened Friday. The gap between "published" and "priced" was one overnight session, and you could have spent it reading.
Two pops off one policy
The week actually gave us the same experiment twice. On Tuesday, August 4, wire reports said the administration was preparing "a minimum import price, or price floor, along with fresh tariffs on polysilicon and related products". No document existed yet. Solar ripped anyway... by the close, per the stockanalysis.com daily closes behind the charts below, Enphase had gained 6.2%, First Solar 4.7%, Sunrun 5.8%, and the Invesco Solar ETF 4.2%. Then Thursday the proclamation landed with real numbers in it, and Friday the sector popped again.
Words on Tuesday, a document on Thursday, and a move off each. The floors themselves are still four months away.
What the document actually says
The proclamation sets minimum import prices of $21 per kilogram for raw polysilicon and $100 per kilogram for ingots and wafers, $0.22 per watt for solar cells, and $0.38 per watt for solar modules, plus a 15% tariff on polysilicon derivatives, with softer treatment for allied trading partners like the EU, Japan, Korea, Taiwan, and the UK. It takes effect December 4, 2026. The stated rationale is national security: US polysilicon production has collapsed from roughly 50% of global share in 2005 to under 2% in 2024. Trump's own framing, in his words: "For decades, America has allowed foreign countries to weaken United States producers in the polysilicon sector, eroding our economic and national security."
Why would a tariff make installers rally? A floor under imported panels raises everyone's input costs, which is bad for a company that buys panels. The market read it differently: a durable policy commitment to domestic solar economics, with the clearest winner being the company that already manufactures here. Our Thursday alert flagged the window that opens first: "The December 4 effective date gives importers a roughly four-month window to front-run, potentially compressing near-term module prices before the floor takes hold."
That sorting is visible in the tape. Over the five weeks into the proclamation, First Solar, the big US manufacturer, gained about 8%, with its Q2 2026 results, reported July 30, feeding the climb. Sunrun, an installer that buys hardware, lost about 22%, most of it after it cut its 2026 guidance on Wednesday evening and slid 10.6% Thursday. Yet on Friday the floor lifted both of them.
Reality check...
Three honest caveats, because this week was noisy. First, all three major indexes had their best week since April, with the S&P 500 up 3.6% and at a record close, so some of Friday's bid was simply beta. The counter is in the second chart: the solar ETF gained 6.9% on the week, call it 7% against the market's 4%. Second, Sunrun's 8.7% Friday pop came one day after a 10.6% earnings-driven drop, so part of it was a bounce. And third, our own alert leaned cautious on the installers short term. It said "FSLR may attract relative strength framing; ENPH, RUN, and SEDG could face selling on margin pressure concerns." The selling never came; the market bid the whole chain. The alert's value was the timing and the terms.
There's a policy caveat too, straight from the same alert: "The MIP enforcement mechanism — dependent on CBP documentation and resale-price compliance — is complex and litigation-prone". Floors that bite in December can be softened, carved out, or challenged before a dollar moves.
The hindsight math, labeled as such
If you had read the proclamation Thursday evening and bought Sunrun at the close, you'd have been up 8.7% by Friday's close. As of Friday's close, the latest data before publication, Sunrun sat at $10.20, still about 22% below its July 1 price. The measurement window here runs from the July 1 baseline through Friday, August 7, chosen to cover both pops and the month of drift before them.
What happens between now and December 4 is genuinely open. Importers could front-run the floor and compress module prices, as our alert suggested; litigation could stall the whole program; the carve-outs could widen. Forward, everything is a maybe. Backward, the tape is just the tape: two pops, one document, and a night of reading time in between.
So the question I keep coming back to: by dinnertime Thursday, the terms were public and quotable. Would you have read them before Friday's open? knowfir.st readers did.
knowfir.st watches primary sources like White House presidential actions, SEC filings, and agency releases, and emails subscribers a short sourced take when something lands, the way the alert quoted above went out the evening the proclamation was signed. Your first feed is free at knowfir.st.