Consumer discretionary stocks ripped higher Wednesday as the sharp decline in oil prices this week triggered a rotation into names that benefit most from lower gas prices and increased disposable income. The Consumer Discretionary Select Sector SPDR Fund (XLY) was up 1.9% in afternoon trading, making it the best-performing sector on the day by a wide margin, as every major sub-sector from airlines to retail to travel booked solid gains.

Here’s the math behind the move: With WTI crude falling below $88 a barrel, the national average gasoline price has dropped to $3.54 per gallon, down from $3.89 a month ago. For the average American household, that translates to roughly $35 to $45 in monthly savings at the pump — money that historically flows straight into discretionary spending categories like dining out, travel, and general retail. Consumer sentiment data has been ticking higher over the past two weeks, and analysts at Morgan Stanley estimate that every $10 decline in oil prices adds roughly 0.3 percentage points to real consumer spending growth.

Airline stocks are flying the highest. The U.S. Global Jets ETF (JETS) surged 3.4%, with Delta Air Lines (DAL) up 3.8%, United Airlines (UAL) gaining 4.1%, and Southwest Airlines (LUV) ahead 2.9%. Lower jet fuel costs directly improve margins, and the airlines are passing some of the savings along through lower fares, which is driving a pickup in advance summer bookings. Travel and leisure names are also participating — Booking Holdings (BKNG) is up 2.2%, Expedia (EXPE) has gained 3.0%, and cruise operator Carnival (CCL) is jumping 4.5%.

Retail stocks are finding buyers as well. Amazon (AMZN) is up 1.5%, contributing to the Nasdaq’s broader advance. Target (TGT) and Walmart (WMT) are each up about 1%, as lower gas prices ease pressure on their lower-income customer base — a cohort that had been pulling back on spending through the first quarter. Home improvement names are also catching a bid, with Home Depot (HD) up 0.9% and Lowe’s (LOW) adding 1.1%. The thesis here is straightforward: when consumers spend less filling their tanks, they spend more filling their carts.