A fourth consecutive defeat under the era of interim Ports boss Pat McGibbon arrived despite taking the lead for the third match in a row.
Ferris was rewarded for his encouraging contribution in recent weeks off the substitutes’ bench with a starting spot at Stangmore Park.
The teenager made his mark with an enthusiastic overall performance capped by a goal around the half-hour mark. The Northern Ireland Schoolboys international guided his textbook header back across the face of goal off a teasing cross by another teenager, Matthew Parker, following good work between Sean Mackle and Chris Casement.
Ferris was introduced to inject fresh energy into the Ports frontline and impressed with his tireless work ethic. He expanded on his role as an enthusiastic sidekick to the experienced Gary Twigg by breaking the deadlock.
The assist from Parker was just one highlight in an assured display at left-back that displayed composure in possession and, in the main, solid defensive work.
Many of Portadown’s most positive periods featured the two young players but with support from senior names such as Michael Gault, Robert Garrett, Twigg and Ken Oman, the latter before limping off with injury.
The Swifts eventually got back on level terms thanks to Gary Liggett before Andrew Mitchell’s injury-time shot. The Ports’ appeals for an offside flag leading up to the first goal and foul against Parker before the second were dismissed by the match officials.
The final whistle signalled another setback but Portadown will aim to build on the small but crucial improvements in a bid to beat the drop.
PORTADOWN: David Miskelly, Chris Ramsey, Garry Breen, Ken Oman, Michael Gault, Chris Casement, Robert Garrett, Sean Mackle, Gary Twigg, Matthew Parker, Nathaniel Ferris. Subs: Martin Marron, Tim Mouncey, Mikey Withers, Marcio Soares (on for Ferris, 89 mins), Pauddy Judge (on for Oman, 56 mins).
Referee: Andrew Davey.