In a 3-quart soup pot, simmer the stock. Add the chicken and poach until opaque and firm, about 10 minutes. Transfer to a plate. Add the carrots to the broth and cook until fork-tender, about 10 minutes. Add the fennel, greens, and beans and simmer.
Shred the chicken into 1-inch strips with your hands. Add to the pot and simmer until the chicken is heated through, about 2 minutes. Season with salt and pepper. Ladle into 4 shallow soup bowls and serve.