Southern California builders, stuck with the largest supply of unsold homes in seven years, have slashed construction to the slowest pace since 2016.

First-quarter data from MetroStudy shows 3,750 new homes went unsold in the four counties covered by the Southern California News Group — an increase of 688 units in a year or 22% and up 37% vs. the five-year average. It was builders’ largest inventory of unsold units since 2012’s first quarter.

As a result, the building pace cooled. In the quarter, Southern California had 8,829 units under construction, down 1,950 or 18% in a year but up 1% vs. the five-year average. It’s still the slowest development pace since the start of 2016.

Local builders are struggling with numerous selling challenges. According to CoreLogic, builders started 2019 with new home sales down 25% from a year ago. First quarter closed sales totaled 2,988 units.

ICYMI: Listings jump 22% as Southern California homeowners rush to sell

Builders bet too heavily on the upscale market, which has been hurt by a pullback of foreign, mainly Chinese, buyers. The more affordable parts of the market have been slowed by higher mortgage rates.

Plus, there’s been a surge of existing homes listed for sale, increasing options for house hunters. The four-county Southern California region had 35,491 listings as of May 2 — 6,373 more than a year earlier, or a 22% increase, according to ReportsOnHousing. Since 2012, listings averaged 30,822 in early May.

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Here’s how MetroStudy saw homebuilding within the region’s counties …

Los Angeles County: 935 finished unsold homes, up 5% over 12 months and up 19% vs. the five-year average. L.A. has 4,231 units under construction, down 2% in a year and up 20% vs. the five-year average. L.A. new-home sales fell 32% to 615 units.

Orange County: 1,108 finished homes for sale up 32% over 12 months and up 85% vs. the five-year average. O.C. has 1,982 units under construction, down 33% in a year and down 17% vs. the five-year average. O.C. new-home sales fell 37% to 706 units.

Inland Empire: 1,707 finished homes for sale up 29% over 12 months and up 25% vs. the five-year average. Riverside and San Bernardino counties have 2,616 units under construction, down 25% in a year and down 9% vs. the five-year average. New-home sales fell 14% to 1,667 units.

The cooling construction pace is a dash of cold reality for those who hope that massive building could ease California’s painfully high cost of living. Even last year’s faster building level was seen by some observers as inadequate to ease homebuying’s cost burdens.