B
BEXT Excel Add-in
Scenario Mockups · Low-Fi
v0.1 · draft
Product Vision · Vibe Trading

The bid tape lives in Excel.
So does the agent.

BEXT meets debt-market traders where they already work. A high-performance Excel Add-in wraps authentication, pricing, MEP6 math, and an agentic AI assistant directly alongside the active worksheet — local-first, encrypted to the BEXT vault, streaming live market context.

Security
Sensitive tapes stay in the .xlsx. Add-in is the secure bridge.
Connectivity
Live MEP6 pricing, Intex cross-ref, TBA market stream.
Intelligence
MAPR agent does the unstructured reasoning a sheet can't.
01
Operational Scenario · Onboarding
Seamless Authentication

Open the BEXT panel inside Excel and authenticate via firm SSO. A persistent encrypted session connects the workbook to the BEXT ecosystem without leaving the spreadsheet.

Blank Workbook — Excel duncan@helmsfund.com
FileHomeInsertDataView BEXT
A1 fx empty
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H
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not connected
Welcome

Sign in to your
debt market desk.

Authenticate once. BEXT keeps your session encrypted to the local workbook and the BEXT Vault.

Local-first session
Your .xlsx never leaves the device. BEXT signs an encrypted handshake bound to this workbook.
MEP6 v6.2.1 · Local-first · build #2042
1 Sign in lives inside Excel. No portal switch. SSO flow opens in a sandboxed task pane and returns a session token bound to this workbook.
2 Persistent across files. Once authenticated, opening any tape in this workspace inherits the session — no repeat logins for the trading day.
3 Encrypted to BEXT Vault. Credentials and connection state are stored in the Vault, not the workbook. Sharing the .xlsx does not leak access.
4 Audit + revoke. Compliance can see every session and revoke device access from the BEXT admin console.
02
Operational Scenario · Task-Oriented Interface
Data Enrichment from Blue File ID

Trader types a Blue File ID into the panel. BEXT looks up the loan record and instantly populates the worksheet with loan-level fields — UPB, FICO, LTV, coupon — already typed and ready to bid.

Tape_Q2_HelmsFund.xlsx — Excel ● BEXT connected
FileHomeInsertData BEXT
A2 fx BF-2026-0418
A
B
C
D
E
F
G
H
1
Blue File
UPB
Rate
Term
FICO
LTV
Coupon
Status
2
BF-2026-0418
358,000
7.250%
360
729
81.5
6.000
↳ enriched
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DC · live
Blue File lookup
BF-
Match found · Helms Pool 41 · written 2026-04-12
Inject into
Preview · 14 fields
UPB$358,000.00
Note Rate7.250%
Term360
FICO729
LTV81.5
Coupon6.000
+ 8 more
1 Zero-step lookup. Type the Blue File ID, hit Pull. No CSV exports, no copy-paste from another system.
2 Field-level preview. See exactly what's being written before it lands in the cells — important for shared tapes.
3 Active-row aware. Inserts into the current selection by default. Cursor convention beats config.
4 Bulk mode. Paste a list of IDs into the lookup box → all rows enriched in one transaction. (Not shown — separate flow.)
03
Operational Scenario · Task-Oriented Interface
Template Generation · LLPA Grid

One click drops a standard LLPA (Loan Level Pricing Adjustment) grid into the worksheet with formulas pre-wired against MEP6. Trader keeps the grid editable for manual overrides.

LLPA_HelmsFund_Q2.xlsx — Excel ● BEXT
FileHomeFormulas BEXT
D5 fx =BEXT.LLPA($D$3, D$4, "v2026-04")
A1 · LLPA Grid · FN30 · Mar 2026
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FN30 — LLPA Grid · v2026-04 (auto-generated by BEXT)
2
LTV bands →
3
FICO ↓
≤60
60-70
70-75
75-80
80-85
>85
4
≥780
FICO band
0.000
0.000
0.125
0.250
0.250
0.375
5
760-779
FICO band
0.000
0.125
0.250
0.375
0.375
0.500
6
740-759
FICO band
0.000
0.250
0.375
0.500
0.625
0.750
7
720-739
FICO band
0.125
0.375
0.500
0.625
0.375
1.000
8
700-719
FICO band
0.250
0.500
0.750
1.000
1.250
1.500
9
680-699
FICO band
0.500
0.875
1.125
1.375
1.625
1.875
10
660-679
FICO band
0.875
1.375
1.625
1.875
2.250
2.500
11
<640
FICO band
1.250
1.875
2.250
2.625
3.000
3.250
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Source
=BEXT.LLPA.SOURCE("v2026-04") · synced 09:47 EDT · editable
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DC
Pick a template
LLPA options
Versionv2026-04
PoolFN30
Insert atA1
Formula sourcelive MEP6
1 Formulas, not values. Cells reference =BEXT.LLPA(...) so the grid stays current as MEP6 versions ship.
2 Editable in place. Trader can manually override any cell — overrides flagged in amber, recoverable to live value with one click.
3 Versioned. Each LLPA grid carries the source version so old tapes can be re-priced against any historical grid.
4 Pricing + Bid Form companions. Same template system covers full pricing sheets and counter-party bid forms.
04
Operational Scenario · Agentic Workflow
Data Intelligence — Anomaly Detection

Trader asks the MAPR agent to find pricing outliers in the active tape. The agent reads the range, queries MEP6, identifies anomalies, and links each finding back to the row in the sheet with a one-click fix.

Tape_Q2_HelmsFund.xlsx — Excel ● MAPR running
FileHomeData BEXT
J5 fx =MEP6.PRICE(C5, D5, "FN30")
A
B
C
D
E
F
G
H
1
Blue File
Pool
UPB
Rate
FICO
LTV
Px
Status
2
BF-2026-0337
FN30
487,500
6.875%
782
68.4
101.84
● ok
3
BF-2026-0338
FN30
312,000
7.125%
744
79.8
102.93
● ok
4
BF-2026-0341
FN15
218,750
6.125%
801
52.1
100.18
● ok
5
BF-2026-0344
FN30
575,400
6.625%
765
71.2
101.84
● ok
6
BF-2026-0346
GN30
198,200
6.250%
708
94.5
102.41
● ok
7
BF-2026-0349
FN30
412,300
7.000%
756
75.3
102.93
● ok
8
BF-2026-0352
FN30
915,800
6.500%
762
69.1
101.84
UPB 2.8σ
9
BF-2026-0358
FN30
351,000
7.250%
732
82.4
102.93
● ok
10
BF-2026-0364
FN15
186,400
5.875%
798
48.7
99.62
● ok
11
BF-2026-0371
FN30
524,000
6.750%
751
77.9
101.84
● ok
12
BF-2026-0378
FN30
462,300
6.625%
734
82.6
102.09
LLPA δ
13
BF-2026-0382
FN30
368,750
7.125%
741
80.2
102.93
● ok
14
BF-2026-0386
GN30
241,500
6.375%
716
96.5
102.41
● ok
15
BF-2026-0450
FN30
488,600
6.250%
751
73.6
101.84
−175bp stale
16
BF-2026-0455
FN30
596,800
6.750%
758
76.4
101.84
● ok
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20
MAPR · 3.8s
Find pricing outliers in this tape. 2.5σ threshold, use today's FN30 snap.
A
MAPR Agent · 3.8s
✓ read_range(A2:H248)
✓ query_mep6(FN30, 09:47Z)
✓ detect_outliers(σ=2.5)
Found 3 anomalies across 247 loans. Basis impact −$48.2K if shipped as-is.
ROW 15 · BF-2026-0450
CRIT −175bp
Rate stale vs current MEP6 snap. Priced off Apr-15 curve.
ROW 8 · BF-2026-0352
WARN 2.8σ
UPB exceeds cluster mean. Verify against Intex pool.
ROW 12 · BF-2026-0378
LLPA δ
FICO 720-740 / LTV 80-85 band reads +0.250, current grid +0.375.
Ask MAPR… ⌘↵
1 One prompt, full audit trail. Tool calls are visible — trader sees exactly what data the agent read and which models it queried.
2 Anomalies link to rows. Each finding is anchored to a specific row in the sheet, with a "Reveal" jump. The sheet itself shows the flag inline.
3 Apply fixes in place. No paste-back. The agent writes corrected values directly into the cells, leaving a tracked change for review.
4 Severity is calibrated. CRIT for basis impact, WARN for distribution outliers, INFO for visibility only.
05
Operational Scenario · Agentic Workflow
MAPR Model Mapping

The agent reviews and conducts MAPR model mapping — translating an unfamiliar tape's columns into BEXT's canonical fields, then verifying each mapping. Reduces manual entry errors that compound through pricing.

CounterpartyA_Tape_Q2.xlsx — Excel (external) ⚠ unmapped tape
FileData BEXT
A1 fx Loan_Number_Internal
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Loan_Number_Internal
Curr_Bal_USD
IntRate_Pct
Rem_Term_Mo
CrScore_FICO
CombLTV
Cpn_Pct
Pool_Type_Cd
↳
→ Blue File ID
→ UPB
→ Note Rate
→ Term
→ FICO
→ LTV
→ Coupon
? Pool
2
CP-A-4471
487500.00
6.875
358
782
68.4
5.500
CONV-30
3
CP-A-4472
312000.00
7.125
360
744
79.8
6.000
CONV-30
4
CP-A-4473
218750.00
6.125
178
801
52.1
5.000
CONV-15
5
CP-A-4474
575400.00
6.625
359
765
71.2
5.500
CONV-30
6
CP-A-4475
198200.00
6.250
360
708
94.5
5.500
GOV-30
7
CP-A-4476
412300.00
7.000
360
756
75.3
6.000
CONV-30
8
CP-A-4477
689500.00
6.500
358
778
65.8
5.500
CONV-30
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MAPR · mapping
Detected external tape with 8 columns. Mapping to BEXT canonical schema…
Column mapping · 7/8 conf 0.94
Loan_Number_Internal
→Blue File ID✓
Curr_Bal_USD
→UPB✓
IntRate_Pct
→Note Rate✓
Rem_Term_Mo
→Term✓
CrScore_FICO
→FICO✓
CombLTV
→LTV✓
Cpn_Pct
→Coupon✓
Pool_Type_Cd
needs review
Values "CONV-30", "CONV-15", "GOV-30" don't match canonical pool codes.
Pre-flight checks
✓ UPB sums to $42.6M (matches counterparty memo)
✓ FICO range 612–812 (in bounds)
✓ No duplicate Blue File IDs
! 3 loans with LTV > 95 (govt only · ok)
1 Detects unfamiliar tapes. When an external file is opened, MAPR proposes column mappings to BEXT canonical fields with confidence scores.
2 Low-confidence flagged for review. Anything below 0.85 confidence gets an explicit choice — agent never silently maps ambiguous fields.
3 Pre-flight reconciliation. Before confirming, agent checks UPB totals, ranges, and uniqueness against counterparty memos.
4 Mapping is reusable. Confirmed mapping is saved per counterparty — next tape from the same source auto-maps without review.
06
Operational Scenario · Deep Workflow Integration
MEP6 Library in Cells

BEXT exposes the MEP6 quant library as native Excel functions. Cells call =MEP6.PRICE(), =MEP6.OAS(), =MEP6.DURATION(). Real pricing math, not wrappers — the same library that powers BEXT's server-side execution.

Pricing_Q2_HelmsFund.xlsx — Excel ● MEP6 v6.2.1
FileHomeFormulas BEXT
F5 fx =MEP6.PRICE(B5, C5, D5, E5, "FN30")
A
B
C
D
E
F
G
H
1
Blue File
UPB
Rate
FICO
LTV
Px (MEP6)
OAS
Duration
2
BF-2026-0337
487,500
6.875
782
68.4
101.84
+47 bp
5.84
3
BF-2026-0338
312,000
7.125
744
79.8
102.93
+52 bp
5.71
4
BF-2026-0341
218,750
6.125
801
52.1
100.18
+41 bp
3.92
5
BF-2026-0344
575,400
6.625
765
71.2
101.84
+48 bp
5.82
6
BF-2026-0346
198,200
6.250
708
94.5
102.41
+58 bp
5.95
7
BF-2026-0349
412,300
7.000
756
75.3
102.93
+50 bp
5.74
8
BF-2026-0352
689,500
6.500
778
65.8
101.84
+46 bp
5.88
9
BF-2026-0358
351,000
7.250
732
82.4
102.93
+55 bp
5.62
10
11
Tape Σ
$3.34M
~$3.42M
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MEP6 lib
Function explorer
ƒx MEP6.PRICE
active
Prices a fixed-rate loan against the MEP6 curve.
PRICE(upb, rate, fico, ltv, pool)
ƒx MEP6.OAS spread
ƒx MEP6.DURATION risk
ƒx MEP6.CONVEXITY risk
ƒx MEP6.LLPA adj
ƒx MEP6.CURVE market
ƒx MEP6.PREPAY model
ƒx MEP6.CASHFLOW vector
Recalc status
Cells using MEP6741
Last snap09:47:12 EDT
Recalclive ●
1 Native Excel functions. MEP6.* appear in the formula picker alongside SUM/IF. Type, autocomplete, drag-fill — standard Excel ergonomics.
2 Real math, not wrappers. The same C++ library that runs BEXT's server-side execution. No drift between desktop and prod pricing.
3 Local-first compute. MEP6 runs in-process. Sheets recalc without round-tripping the cloud — work offline against the last snap.
4 Streaming inputs. Curve/snap inputs update from the BEXT market stream; cells using MEP6.PRICE recalc on tick.
07
Operational Scenario · Deep Workflow Integration
Live Market Updates

Streaming TBA prices, bid status, and curve moves arrive through the BEXT panel. Cells that depend on the market recalculate automatically; recently-changed rows pulse so the trader sees what just moved.

Tape_Q2_HelmsFund.xlsx — Excel streaming · 09:47:38
FileHomeData BEXT
F2 fx =MEP6.PRICE(B2:E2, BEXT.MARKET.SNAP())
A
B
C
D
E
F
G
H
1
Blue File
UPB
Rate
FICO
LTV
Px (live)
Δ tick
Status
2
BF-2026-0337
487,500
6.875
782
68.4
101.86
▲ 0.02
● bidding
3
BF-2026-0338
312,000
7.125
744
79.8
102.96
▲ 0.03
● bidding
4
BF-2026-0341
218,750
6.125
801
52.1
100.18
·00
● ok
5
BF-2026-0344
575,400
6.625
765
71.2
101.86
▲ 0.02
● bidding
6
BF-2026-0346
198,200
6.250
708
94.5
102.41
·00
● ok
7
BF-2026-0349
412,300
7.000
756
75.3
102.93
·00
★ awarded
8
BF-2026-0352
689,500
6.500
778
65.8
101.86
▲ 0.02
● bidding
9
BF-2026-0358
351,000
7.250
732
82.4
102.93
·00
● ok
10
BF-2026-0364
186,400
5.875
798
48.7
99.62
·00
✕ lost
11
BF-2026-0371
524,000
6.750
751
77.9
101.86
▲ 0.02
● bidding
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live
TBA · live stream
FN30 5.5 101-24+ ▲02
FN30 6.0 102-29 ▲05
FN15 5.0 100-08 ·00
GN II 5.5 102-18 ▲01
UMBS 6.0 103-08+ ▲03
10Y UST 4.187 ▼0.4
Bid status · 247 loans
Bidding232
Awarded12 ★
Lost3 ✕
Realized basis$1.42M
Recent ticks
09:47:38FN30 5.5 ▲02
09:47:21★ 0349 awarded
09:47:12FN30 6.0 ▲05
09:46:58✕ 0364 lost
09:46:43snap pushed
Live
FN30 5.5 101-24+ ▲02 FN30 6.0 102-29 ▲05 FN15 5.0 100-08 ·00 GN II 5.5 102-18 ▲01 UMBS 6.0 103-08+ ▲03 10Y UST 4.187 ▼0.4 BEXT BTI 99.84 ▲0.12 FN30 5.5 101-24+ ▲02 FN30 6.0 102-29 ▲05 FN15 5.0 100-08 ·00 GN II 5.5 102-18 ▲01 UMBS 6.0 103-08+ ▲03 10Y UST 4.187 ▼0.4 BEXT BTI 99.84 ▲0.12
1 Pulse on change. Rows that just recalculated highlight in mint. Trader's eye is drawn to what moved without scanning the whole tape.
2 Bid lifecycle visible. ● bidding, ★ awarded, ✕ lost — status streams in from BEXT execution and lives on the row.
3 Recent ticks log. Side panel shows the timeline of recent events for context: price moves, awards, snap pushes.
4 Offline-safe. If the stream drops, cells freeze at the last snap and a banner notes "stale." Local-first means no broken sheets.