
	Principal amount				Carrying amount
	March 31,		December 31,		March 31,		December 31,
	2021		2020		2021		2020
6.375% Senior Notes due December 2021	$	38	$	38	$	38	$	38
5.52% Senior Secured Notes due May 2022		89		111		88		111
3.80% Senior Notes due October 2022		27		27		27		27
0.50% Exchangeable Senior Bonds due January 2023		140		463		139		462
5.375% Senior Secured Notes due May 2023		362		364		359		360
5.875% Senior Secured Notes due January 2024		544		585		536		577
7.75% Senior Secured Notes due October 2024		360		360		354		354
6.25% Senior Secured Notes due December 2024		375		375		370		369
6.125% Senior Secured Notes due August 2025		435		468		428		461
7.25% Senior Notes due November 2025		411		411		406		405
4.00% Senior Guaranteed Exchangeable Bonds due December 2025		294		—		260		—
7.50% Senior Notes due January 2026		569		569		565		565
2.50% Senior Guaranteed Exchangeable Bonds due January 2027		238		238		274		277
11.50% Senior Guaranteed Notes due January 2027		687		687		1,113		1,139
6.875% Senior Secured Notes due February 2027		550		550		543		542
8.00% Senior Notes due February 2027		612		612		607		606
7.45% Notes due April 2027		52		52		51		51
8.00% Debentures due April 2027		22		22		22		22
7.00% Notes due June 2028		261		261		265		266
7.50% Notes due April 2031		396		396		394		394
6.80% Senior Notes due March 2038		610		610		605		605
7.35% Senior Notes due December 2041		177		177		176		176
Total debt		7,249		7,376		7,620		7,807

Less debt due within one year
6.375% Senior Notes due December 2021		38		38		38		38
5.52% Senior Secured Notes due May 2022		71		93		70		92
5.375% Senior Secured Notes due May 2023		47		47		46		46
5.875% Senior Secured Notes due January 2024		83		83		80		80
7.75% Senior Secured Notes due October 2024		60		60		58		58
6.25% Senior Secured Notes due December 2024		62		62		60		60
6.125% Senior Secured Notes due August 2025		66		66		64		64
2.50% Senior Guaranteed Exchangeable Bonds due January 2027		—		—		6		6
11.50% Senior Guaranteed Notes due January 2027		—		—		70		61
6.875% Senior Secured Notes due February 2027		34		—		32		—
Total debt due within one year		461		449		524		505
Total long-term debt	$	6,788	$	6,927	$	7,096	$	7,302


	Three months ended March 31, 2021						Three months ended March 31, 2020
	Exchanged		Repurchased		Total		Redeemed		Repurchased		Total
6.50% Senior Notes due November 2020	$	—	$	—	$	—	$	—	$	8	$	8
6.375% Senior Notes due December 2021		—		—		—		—		38		38
3.80% Senior Notes due October 2022		—		—		—		—		3		3
0.50% Exchangeable Senior Bonds due January 2023		323		—		323		—		—		—
5.375% Senior Secured Notes due May 2023		—		1		1		—		6		6
9.00% Senior Notes due July 2023		—		—		—		714		—		714
Aggregate principal amount retired	$	323	$	1	$	324	$	714	$	55	$	769

Aggregate cash payment	$	11	$	1	$	12	$	767	$	46	$	813
Aggregate principal amount of debt issued in exchanges	$	294	$	—	$	294	$	—	$	—	$	—
Aggregate net gain (loss)	$	51	$	—	$	51	$	(65)	$	8	$	(57)

Schedule of debt

Exchange terms—At March 31, 2021, the current exchange rates, expressed as the number of Transocean Ltd. shares per $1,000 note, and the implied exchange prices per Transocean Ltd. share for our exchangeable bonds were as follows:


			Implied
	Exchange		exchange
	rate		price
0.50% Exchangeable Senior Bonds due January 2023		97.29756	$	10.28
4.00% Senior Guaranteed Exchangeable Bonds due December 2025		190.47620		5.25
2.50% Senior Guaranteed Exchangeable Bonds due January 2027		162.16260		6.17

Effective interest rates and fair values—At March 31, 2021, the effective interest rates and estimated fair values of our exchangeable bonds were as follows (in millions):


	Effective		Fair
	interest rate		value
0.50% Exchangeable Senior Bonds due January 2023		0.5%	$	104
4.00% Senior Guaranteed Exchangeable Bonds due December 2025		6.9%		280
2.50% Senior Guaranteed Exchangeable Bonds due January 2027		0.0%		195