1. Paypal
2016 Rank: No. 307

Paypal, the payment juggernaut of Silicon Valley, is by no means a new name to the average consumer. But the company is a fresh face to the Fortune 500 after a high-profile split from eBay last summer. During its first year as a standalone company, Paypal raked in a revenue of $9.2 billion—enough to lead this year’s cohort of newcomers at No. 307. Also read: How PayPal Plans to Get Back on Top in Digital Payments from the June 15, 2016 issue of Fortune.

2. Univar
2016 Rank: No. 315

Univar, a chemical distribution company based in Illinois, is on a hunt for growth. After going public last June, Univar completed two back-to-back acquisitions of Arrow Chemical and Weavertown Environmental Group last winter. Despite a 13% dip in sales, net income for 2015 was $16.5 million.

3. Veritiv
2016 Rank: No. 323

Last July, the paper-products giant International Paper Company (2015 Rank: No. 127) spun off its underperforming distribution business, xpedx, and merged it with Unisource Worldwide. The resultant company was Veritiv, a print, publishing, and packaging distributor. For this well-pedigreed company, life has been rosy thus far: revenue in 2015 totaled $8.7 billion.

4. XPO Logistics
2016 Ranking: No. 353
2015 Rank: No. 909

XPO debuts on this year’s list following a stunning 419.8% increase in revenue, the sum amounting to $7.62 billion. The Connecticut shipping provider’s spectacular growth follows an ambitious slate of acquisitions completed over the course of 2015: UX Specialized Logistics for $59 million; Bridge Terminal Transport for $100 million; Con-Way Inc. for $3 billion; and Norbert Dentressangle for $3.53 billion.

5. Baxalta
2016 Ranking: No. 420

Baxalta, a biopharmeceutical company that specializes in treating rare conditions, was spun off from the healthcare giant Baxter International (ranked No. 286 on the 2015 list) last July. Earning $6.1 billion in revenue its inaugural year, the young company is looking forward to greater growth as it awaits the conclusion of a $32 billion merger with Shire.

6. Zimmer Biomet Holdings
2016 Ranking: No. 431
2015 Rank: No. 555 (as Zimmer Holdings)

Zimmer Biomet was hatched in 2015 from a $14 billion mega merger between two orthopedic powerhouses—Zimmer and Biomet. The medical manufacturing scion reported revenue of $6.0 billion in 2015, amounting to a 28.3% year-over-year increase.

7. Genesis Healthcare
2016 Ranking: No. 457

Genesis Healthcare, a Pennsylvania-based provider of skilled nursing and assisted living services, has become one of the nation’s largest care providers after concluding a $5.5 billion merger with Skilled Healthcare Group. Genesis’ growth has been further enhanced by a $240 million acquisition of nursing facilities from Revera in 2015.

8. Envision Healthcare Holdings
2016 Ranking: No. 469
2015 Rank: No. 587

Envision Healthcare, an emergency healthcare provider and ambulance operator, ascends into the Fortune 500 after generating $5.45 billion in revenue last year. For a pricetag of $1.4 billion, the company accelerated its growth last year with a series of nine acquisitions. Envision’s new portfolio includes Rural/Metro, a privately-held ambulance and fire protection company, acquired for $620 million.

9. Arthur J. Gallagher
2016 Ranking: No. 471
2015 Rank: No. 558

To say that Arthur J. Gallagher had a busy year is an understatement. In 2015, the Illinois-based insurance broker acquired 42 companies—15 of which were completed in the fourth quarter—with estimated revenues totaling $223 million. The company’s net revenue amounted to $5.4 billion.

10. Markel
2016 Ranking: No. 476
2015 Rank: No. 504

Markel, a speciality and small business insurer headquartered in Richmond, Virginia, concluded its third decade as a public company with $5.4 billion in revenue. Alongside strong underwriting results, the company’s growth has been fueled by two acquisitions: CATCo, a Bermuda-based investment management business, and CapTech, a Richmond-based management and IT consulting firm.

11. Raymond James Financial
2016 Ranking: No. 482
2015 Rank: No. 521

In addition to extending its naming rights deal with the Tampa Bay Buccaneers’ stadium, Raymond James has added its brand to the Fortune 500 roster. Having achieved a record revenue of $5.20 billion in 2015, the Florida-based financial services company is expanding its locations in the Northeast and Midwest.

12. ABM Industries
2016 Ranking: No. 485
2015 Rank: No. 515

ABM is making steady progress toward the “2020 Vision” of long-term profitable growth it announced last September. The facility services corporation accumulated $4.9 billion in revenue last year—up 5.3% from the previous year. Its growth was further bolstered by two new acquisitions—CTS and Westway Services—extending the New York company’s reach to DC and the UK.

13. Citizens Financial Group
2016 Ranking: No. 486

Last November, Citizens Financial split from its foreign parent—the Royal Bank of Scotland—after nearly three decades of union. The trials of separation evidently didn’t impede the newly-independent bank’s solo performance: net income totaled $840 million in 2015.

14. Lam Research
2016 Ranking: No. 491
2015 Rank: No. 563

Named one of Fortune’s 100 Fastest Growing Companies in 2012, Lam’s strong history of growth has now propelled the company to the ranks of the Fortune 500. The semiconductor equipment maker, based in Fremont, Calif., reported revenue of $5.3 billion in 2015.

15. Burlington Stores
2016 Ranking: No. 500
2015 Rank: No. 532

Headquartered in Florence, New Jersey, this popular off-price retailer rounds out this year’s roster of newcomers at No. 500. Despite an unseasonably warm winter, the corporation best known for its discounted coats reported sales growth of 5.9% for fiscal 2015, posting $5.1 billion in revenue.

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