7	Trade receivables

Trade receivables at December 31, 2017 and 2016, are summarized as follows:

	2017			2016
Maritime
Parcel tankers	$	44,024		$	42,069
Shipyards		30,015			23,781
Offshore vessels		28,716			496,579
Tugboats		12,401			25,440
Bulk Carrier		10,698			-
Tankers		-			84,313
Others		25			26

Ports and terminals
Shipping agencies		48,648			78,602
Port services		6,717			13,654
Commercial leases		434			599

Logistics, warehousing and other businesses
Warehousing		55,848			37,415
Repair of containers		40,730			27,471
Automotive services		689			891
Other businesses		2			882
Total trade receivables		278,947			831,722
Allowance for doubtful accounts		(28,310	)		(35,353	)
	$	250,637		$	796,369

The Company, through its subsidiaries TMM DM and Transportacion Maritima Mexicana, S.A. de C.V., signed an adhesion agreement to the productive chain program of Nacional Financiera, S.N.C. (Nafin), by implementing lines of factoring as a source of financing to reduce the liquidity risk and minimize the effect of the policies of extending the payment periods of the main customer of the Company.

Transactions were carried out in 2017 with Greensill Capital Ltd (‘Greensill’), and Grupo Financiero Ve por Mas, S. A. I.B.M. Grupo Financiero Ve por Mas (Ve por Mas) through the Nafin portal in a total amount of $279.8 million, at an average Libor rate + 2.90 for Ve por Mas with a 10% discount on the total of the documents to be discounted and Libor + 2.95 with Greensill without discount.

During 2016 transactions were carried out with Greensill, Ve por Más, Financiera Bajio, S.A. de C.V. SOFOM, E.R., Banca Mifel, S.A. I.B.M. and Grupo Financiero Mifel, through the portal of Nafin amounting to a total of $397.2 million, at an average Libor rate 3m + 2.90 for Mexican institutions and Libor 3m + 3.95 for Greensill.