# Mackay Shields LLC 13F holdings

> Latest reported SEC 13F equity book. Teaser: top 10 of 111 long-equity positions.
> CIK 61227. Latest filing Q1 2026, as of quarter end 2026-03-31. Long-equity book $2.7B.

## Top holdings (teaser)

| # | Ticker | Issuer | Value | % of book | Change |
|---|--------|--------|-------|-----------|--------|
| 1 | LITE 0.5 06/15/28 | Lumentum Hldgs Inc | $143.6M | 5.3% | Reduced |
| 2 | WDC 3 11/15/28 | Western Digital Corp | $110.8M | 4.1% | Reduced |
| 3 | AEIS 2.5 09/15/28 | Advanced Energy Inds | $95.4M | 3.5% | Reduced |
| 4 | MIRM 4 05/01/29 | Mirum Pharmaceuticals Inc | $69.0M | 2.5% | Reduced |
| 5 | QXO 5.5 05/15/28 | Qxo Inc | $65.3M | 2.4% | Reduced |
| 6 | LNTH 2.625 12/15/27 | Lantheus Hldgs Inc | $61.2M | 2.2% | Reduced |
| 7 | MKSI 1.25 06/01/30 | MKS Inc. | $60.4M | 2.2% | Reduced |
| 8 | CABO 1.125 03/15/28 | Cable One Inc | $58.4M | 2.1% | Added |
| 9 | TTEK 2.25 08/15/28 | Tetra Tech Inc New | $57.2M | 2.1% | Reduced |
| 10 | UBER 0.875 12/01/28 2028 | Uber Technologies Inc | $54.6M | 2.0% | Added |

## Latest moves

Bought: ITGR 1.875 03/15/30, ORCL 6.5 01/15/29 D, U 0 03/15/30
Sold: LITE 0.5 06/15/28, WDC 3 11/15/28, AEIS 2.5 09/15/28

Counts and totals reflect the 13F filers and securities Arkolith tracks, not the entire institutional universe. Option legs are excluded from the book above.

## Full data via the API and MCP

This page is a teaser. The complete book, full quarter-over-quarter history, and per-datapoint
provenance are available through the metered REST API and MCP server.

- Endpoint: https://arkolith.com/api/mcp (transport: streamable-http)
- Auth: Bearer API key. Mint one and copy a ready-to-paste command at https://arkolith.com/connect
- Claude Code: `claude mcp add --transport http arkolith https://arkolith.com/api/mcp --header "Authorization: Bearer YOUR_API_KEY"`
- Discovery: `tools/list` is free; `tools/call` is metered by credits.

### Machine-readable
- Tool catalog JSON: https://arkolith.com/api/mcp/catalog
- MCP descriptor: https://arkolith.com/.well-known/mcp.json
- OpenAPI 3.1 REST spec: https://arkolith.com/openapi.json
- Full LLM guide: https://arkolith.com/llms-full.txt
- Human docs: https://arkolith.com/docs

## Source and method

- Source: SEC EDGAR 13F-HR (public domain). Long-equity positions only (option legs excluded). Filed quarterly, about a 45-day lag.
- Primary source: https://www.sec.gov/Archives/edgar/data/61227/000108514626000371/xslForm13F_X02/primary_doc.xml
- Human page: https://arkolith.com/fund/mackay-shields-llc-61227
- Per-datapoint lineage: call the `provenance.get` MCP tool for the source URL and fetch history behind any figure.

Paid product with a one-time evaluation grant at signup (no card to evaluate). Most calls cost 1 credit (~$0.01); heavier point-in-time / cross-source tools cost more.

_Latest disclosed public filings. Data, not investment advice._