NiSource added roughly $1.1 billion of revenue in the three months ended March 31, 2026, almost doubling the comparable period’s haul. Operating income rose from $297.5 million to $819.2 million, and net income jumped to $507.1 million from $94.7 million.
That is the clean version of the filing: more sales, much more profit, and operating margin up 11.3 percentage points to 35.3%. The less tidy detail is that cash fell 24.3% to $71.9 million, while accounts receivable climbed 76.2% to $1.2 billion.
NiSource does not identify a specific operating cause for the jump in the supplied receipts. What the numbers do show is a business that booked a powerful earnings increase while converting less of the latest period into free cash. Free-cash-flow margin was negative 15.6%, down 9.5 percentage points on the comparable basis.
The balance-sheet movement matters because the earnings surge is not the only measure of financial capacity. A receivable is revenue not yet collected, and the company had more of those claims outstanding even as its cash balance declined. Capex fell 58.4% year over year, but that did not keep free cash flow from moving further below zero.
The filing’s first explicit pressure point is borrowing cost. NiSource says a 100-basis-point move in short-term rates would change interest expense by $2.0 million for the latest three months. That is small beside the $521.7 million increase in operating income, but it identifies a recurring sensitivity around the cash and debt machinery behind the result.
"Based upon average borrowings and debt obligations subject to fluctuations in short-term market interest rates, an increase (or decrease) in short-term interest rates of 100 basis points (1%) would have increased (or decreased) interest expense by $2.0 million for the three months ended March 31, 2026 and $2.5 million for the three months ended March 31, 2025, respectively."
NiSource, 10-Q, May 6, 2026
The plain-English translation is that short-term rates are not the main explanation for the profit change, but they remain attached to the company’s revolving credit, commercial paper, and accounts receivable programs. The filing also says future long-term debt issuance could be influenced by benchmark rates.
"Interest Rate Risk We are exposed to interest rate risk as a result of changes in interest rates on borrowings under our revolving credit agreement, commercial paper program, and accounts receivable programs, which have interest rates that are indexed to short-term market interest rates."
NiSource, 10-Q, May 6, 2026
NiSource’s annual record gives the surge some history. Revenue rose 23.5% in 2025 to $6.5 billion, and operating cash flow covered net income 2.54 times in that year. The latest three months therefore arrive after a year of reported growth, not from a company with no recent expansion, but the cash and receivables pattern is materially different from the annual cash-conversion read.
At the latest close, NiSource shares were $44.54, nearly unchanged on August 4. The unresolved question is not whether earnings rose; it is how much of this latest earnings increase will be reflected in collected cash as receivables come due.
Source: NiSource’s 2026-05-06 Form 10-Q and company-reported 2025 annual results.